Make sure that the pref browser.startup.homepage is set to the URL you want in about:config

• Go to about:config via Address Bar > Click the I'll be careful, I promise! to continue, search for 'browser.startup.homepage and make sure it's set to the site you want. If it's not, right click and click Modify then edit it to your liking.

A third party app may be doing this as well.
Can I have your troubleshooting information?

• Go to Help > Troubleshooting Information > Copy text to clipboard and paste (CTRL + V/Command + V) your response into a new reply.

Application Basics
------------------
Name: Firefox
Version: 28.0
User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0
Crash Reports for the Last 3 Days
---------------------------------
All Crash Reports (including 1 pending crash in the given time range)
Extensions
----------
Name: Norton Toolbar
Version: 2013.4.8.1
Enabled: true
ID: {2D3F3651-74B9-4795-BDEC-6DA2F431CB62}
Name: Norton Vulnerability Protection
Version: 12.2.0.5 - 1
Enabled: true
ID: {BBDA0591-3099-440a-AA10-41764D9DB4DB}
Name: HP Smart Web Printing
Version: 4.60
Enabled: false
ID: smartwebprinting@hp.com
Important Modified Preferences
------------------------------
accessibility.browsewithcaret: true
accessibility.typeaheadfind.flashBar: 0
browser.cache.disk.capacity: 358400
browser.cache.disk.smart_size.first_run: false
browser.cache.disk.smart_size.use_old_max: false
browser.cache.disk.smart_size_cached_value: 358400
browser.places.smartBookmarksVersion: 6
browser.search.useDBForOrder: true
browser.sessionstore.upgradeBackup.latestBuildID: 20140314220517
browser.startup.homepage: www.gmail.com
browser.startup.homepage_override.buildID: 20140314220517
browser.startup.homepage_override.mstone: 28.0
browser.tabs.warnOnClose: false
browser.urlbar.default.behavior: 1
dom.disable_open_during_load: false
dom.mozApps.used: true
dom.w3c_touch_events.expose: false
extensions.lastAppVersion: 28.0
gfx.direct3d.checkDX10: false
gfx.direct3d.last_used_feature_level_idx: 1
network.cookie.prefsMigrated: true
places.database.lastMaintenance: 1398084132
places.history.expiration.transient_current_max_pages: 104858
places.history.expiration.transient_optimal_database_size: 167772160
plugin.disable_full_page_plugin_for_types: application/pdf
plugin.importedState: true
print.print_printer: HP Officejet Pro K550 Series
print.printer_EPSON_WP-4530_Series.print_bgcolor: false
print.printer_EPSON_WP-4530_Series.print_bgimages: false
print.printer_EPSON_WP-4530_Series.print_colorspace:
print.printer_EPSON_WP-4530_Series.print_command:
print.printer_EPSON_WP-4530_Series.print_downloadfonts: false
print.printer_EPSON_WP-4530_Series.print_duplex: 212204480
print.printer_EPSON_WP-4530_Series.print_edge_bottom: 0
print.printer_EPSON_WP-4530_Series.print_edge_left: 0
print.printer_EPSON_WP-4530_Series.print_edge_right: 0
print.printer_EPSON_WP-4530_Series.print_edge_top: 0
print.printer_EPSON_WP-4530_Series.print_evenpages: true
print.printer_EPSON_WP-4530_Series.print_footercenter:
print.printer_EPSON_WP-4530_Series.print_footerleft: &PT
print.printer_EPSON_WP-4530_Series.print_footerright: &D
print.printer_EPSON_WP-4530_Series.print_headercenter:
print.printer_EPSON_WP-4530_Series.print_headerleft: &T
print.printer_EPSON_WP-4530_Series.print_headerright: &U
print.printer_EPSON_WP-4530_Series.print_in_color: true
print.printer_EPSON_WP-4530_Series.print_margin_bottom: 0.5
print.printer_EPSON_WP-4530_Series.print_margin_left: 0.5
print.printer_EPSON_WP-4530_Series.print_margin_right: 0.5
print.printer_EPSON_WP-4530_Series.print_margin_top: 0.5
print.printer_EPSON_WP-4530_Series.print_oddpages: true
print.printer_EPSON_WP-4530_Series.print_orientation: 0
print.printer_EPSON_WP-4530_Series.print_page_delay: 50
print.printer_EPSON_WP-4530_Series.print_paper_data: 1
print.printer_EPSON_WP-4530_Series.print_paper_height: 11.00
print.printer_EPSON_WP-4530_Series.print_paper_name:
print.printer_EPSON_WP-4530_Series.print_paper_size_type: 0
print.printer_EPSON_WP-4530_Series.print_paper_size_unit: 0
print.printer_EPSON_WP-4530_Series.print_paper_width: 8.50
print.printer_EPSON_WP-4530_Series.print_plex_name:
print.printer_EPSON_WP-4530_Series.print_resolution: 131085
print.printer_EPSON_WP-4530_Series.print_resolution_name:
print.printer_EPSON_WP-4530_Series.print_reversed: false
print.printer_EPSON_WP-4530_Series.print_scaling: 1.00
print.printer_EPSON_WP-4530_Series.print_shrink_to_fit: true
print.printer_EPSON_WP-4530_Series.print_to_file: false
print.printer_EPSON_WP-4530_Series.print_unwriteable_margin_bottom: 0
print.printer_EPSON_WP-4530_Series.print_unwriteable_margin_left: 0
print.printer_EPSON_WP-4530_Series.print_unwriteable_margin_right: 0
print.printer_EPSON_WP-4530_Series.print_unwriteable_margin_top: 0

I should've read your post more carefully....

You said:

Instead it opens my last pages opened.

You probably have the setting to do that. See if that is true or not

• Click the orange Firefox button then go to Options
• Click the General section
• Where it says When Firefox starts make sure "Show my home page" is selected and not "Show my windows and tabs from last time". If this is selected, simply change it.

It's been set to that, but it still opens my last history instead of my home page.

print.printer_Fax_-_HP_Officejet_Pro_8600.print_unwriteable_margin_top: 0 print.printer_HP_Officejet_Pro_8600.print_bgcolor: false print.printer_HP_Officejet_Pro_8600.print_bgimages: false print.printer_HP_Officejet_Pro_8600.print_colorspace: print.printer_HP_Officejet_Pro_8600.print_command: print.printer_HP_Officejet_Pro_8600.print_downloadfonts: false print.printer_HP_Officejet_Pro_8600.print_duplex: 212204480 print.printer_HP_Officejet_Pro_8600.print_edge_bottom: 0 print.printer_HP_Officejet_Pro_8600.print_edge_left: 0 print.printer_HP_Officejet_Pro_8600.print_edge_right: 0 print.printer_HP_Officejet_Pro_8600.print_edge_top: 0 print.printer_HP_Officejet_Pro_8600.print_evenpages: true print.printer_HP_Officejet_Pro_8600.print_footercenter: print.printer_HP_Officejet_Pro_8600.print_footerleft: &PT print.printer_HP_Officejet_Pro_8600.print_footerright: &D print.printer_HP_Officejet_Pro_8600.print_headercenter: print.printer_HP_Officejet_Pro_8600.print_headerleft: &T print.printer_HP_Officejet_Pro_8600.print_headerright: &U print.printer_HP_Officejet_Pro_8600.print_in_color: true print.printer_HP_Officejet_Pro_8600.print_margin_bottom: 0.5 print.printer_HP_Officejet_Pro_8600.print_margin_left: 0.5 print.printer_HP_Officejet_Pro_8600.print_margin_right: 0.5 print.printer_HP_Officejet_Pro_8600.print_margin_top: 0.5 print.printer_HP_Officejet_Pro_8600.print_oddpages: true print.printer_HP_Officejet_Pro_8600.print_orientation: 0 print.printer_HP_Officejet_Pro_8600.print_page_delay: 50 print.printer_HP_Officejet_Pro_8600.print_paper_data: 1 print.printer_HP_Officejet_Pro_8600.print_paper_height: 11.00 print.printer_HP_Officejet_Pro_8600.print_paper_name: print.printer_HP_Officejet_Pro_8600.print_paper_size_type: 0 print.printer_HP_Officejet_Pro_8600.print_paper_size_unit: 0 print.printer_HP_Officejet_Pro_8600.print_paper_width: 8.50 print.printer_HP_Officejet_Pro_8600.print_plex_name: print.printer_HP_Officejet_Pro_8600.print_resolution: 131085 print.printer_HP_Officejet_Pro_8600.print_resolution_name: print.printer_HP_Officejet_Pro_8600.print_reversed: false print.printer_HP_Officejet_Pro_8600.print_scaling: 1.00 print.printer_HP_Officejet_Pro_8600.print_shrink_to_fit: true print.printer_HP_Officejet_Pro_8600.print_to_file: false print.printer_HP_Officejet_Pro_8600.print_unwriteable_margin_bottom: 0 print.printer_HP_Officejet_Pro_8600.print_unwriteable_margin_left: 0 print.printer_HP_Officejet_Pro_8600.print_unwriteable_margin_right: 0 print.printer_HP_Officejet_Pro_8600.print_unwriteable_margin_top: 0 print.printer_HP_Officejet_Pro_K550_Series.print_bgcolor: false print.printer_HP_Officejet_Pro_K550_Series.print_bgimages: false print.printer_HP_Officejet_Pro_K550_Series.print_command: print.printer_HP_Officejet_Pro_K550_Series.print_downloadfonts: false print.printer_HP_Officejet_Pro_K550_Series.print_edge_bottom: 0 print.printer_HP_Officejet_Pro_K550_Series.print_edge_left: 0 print.printer_HP_Officejet_Pro_K550_Series.print_edge_right: 0 print.printer_HP_Officejet_Pro_K550_Series.print_edge_top: 0 print.printer_HP_Officejet_Pro_K550_Series.print_evenpages: true print.printer_HP_Officejet_Pro_K550_Series.print_footercenter: print.printer_HP_Officejet_Pro_K550_Series.print_footerleft: &PT print.printer_HP_Officejet_Pro_K550_Series.print_footerright: &D print.printer_HP_Officejet_Pro_K550_Series.print_headercenter: print.printer_HP_Officejet_Pro_K550_Series.print_headerleft: &T print.printer_HP_Officejet_Pro_K550_Series.print_headerright: &U print.printer_HP_Officejet_Pro_K550_Series.print_in_color: true print.printer_HP_Officejet_Pro_K550_Series.print_margin_bottom: 0.5 print.printer_HP_Officejet_Pro_K550_Series.print_margin_left: 0.5 print.printer_HP_Officejet_Pro_K550_Series.print_margin_right: 0.5 print.printer_HP_Officejet_Pro_K550_Series.print_margin_top: 0.5 print.printer_HP_Officejet_Pro_K550_Series.print_oddpages: true print.printer_HP_Officejet_Pro_K550_Series.print_orientation: 0 print.printer_HP_Officejet_Pro_K550_Series.print_page_delay: 50 print.printer_HP_Officejet_Pro_K550_Series.print_paper_data: 1 print.printer_HP_Officejet_Pro_K550_Series.print_paper_height: 11.00 print.printer_HP_Officejet_Pro_K550_Series.print_paper_size_type: 0 print.printer_HP_Officejet_Pro_K550_Series.print_paper_size_unit: 0 print.printer_HP_Officejet_Pro_K550_Series.print_paper_width: 8.50 print.printer_HP_Officejet_Pro_K550_Series.print_reversed: false print.printer_HP_Officejet_Pro_K550_Series.print_scaling: 1.00 print.printer_HP_Officejet_Pro_K550_Series.print_shrink_to_fit: true print.printer_HP_Officejet_Pro_K550_Series.print_to_file: false print.printer_HP_Officejet_Pro_K550_Series.print_unwriteable_margin_bottom: 0 print.printer_HP_Officejet_Pro_K550_Series.print_unwriteable_margin_left: 0 print.printer_HP_Officejet_Pro_K550_Series.print_unwriteable_margin_right: 0 print.printer_HP_Officejet_Pro_K550_Series.print_unwriteable_margin_top: 0 print.printer_PDF995.print_bgcolor: false print.printer_PDF995.print_bgimages: false print.printer_PDF995.print_colorspace: print.printer_PDF995.print_command: print.printer_PDF995.print_downloadfonts: false print.printer_PDF995.print_duplex: 212204480 print.printer_PDF995.print_edge_bottom: 0 print.printer_PDF995.print_edge_left: 0 print.printer_PDF995.print_edge_right: 0 print.printer_PDF995.print_edge_top: 0 print.printer_PDF995.print_evenpages: true print.printer_PDF995.print_footercenter: print.printer_PDF995.print_footerleft: &PT print.printer_PDF995.print_footerright: &D print.printer_PDF995.print_headercenter: print.printer_PDF995.print_headerleft: &T print.printer_PDF995.print_headerright: &U print.printer_PDF995.print_in_color: true print.printer_PDF995.print_margin_bottom: 0.5 print.printer_PDF995.print_margin_left: 0.5 print.printer_PDF995.print_margin_right: 0.5 print.printer_PDF995.print_margin_top: 0.5 print.printer_PDF995.print_oddpages: true print.printer_PDF995.print_orientation: 0 print.printer_PDF995.print_page_delay: 50 print.printer_PDF995.print_paper_data: 1 print.printer_PDF995.print_paper_height: 11.00 print.printer_PDF995.print_paper_name: print.printer_PDF995.print_paper_size_type: 0 print.printer_PDF995.print_paper_size_unit: 0 print.printer_PDF995.print_paper_width: 8.50 print.printer_PDF995.print_plex_name: print.printer_PDF995.print_resolution: 131085 print.printer_PDF995.print_resolution_name: print.printer_PDF995.print_reversed: false print.printer_PDF995.print_scaling: 1.00 print.printer_PDF995.print_shrink_to_fit: true print.printer_PDF995.print_to_file: false print.printer_PDF995.print_unwriteable_margin_bottom: 0 print.printer_PDF995.print_unwriteable_margin_left: 0 print.printer_PDF995.print_unwriteable_margin_right: 0 print.printer_PDF995.print_unwriteable_margin_top: 0 privacy.cpd.offlineApps: true privacy.cpd.siteSettings: true privacy.donottrackheader.enabled: true privacy.popups.showBrowserMessage: false privacy.sanitize.migrateFx3Prefs: true privacy.sanitize.timeSpan: 0 security.warn_viewing_mixed: false storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1397327322

user.js Preferences

Your profile folder contains a user.js file, which includes preferences that were not created by Firefox.

Graphics

Adapter Description: Intel(R) HD Graphics Adapter Drivers: igdumd64 igd10umd64 igdumdx32 igd10umd32 Adapter RAM: Unknown Device ID: 0x0042 Direct2D Enabled: true DirectWrite Enabled: true (6.2.9200.16571) Driver Date: 8-31-2011 Driver Version: 8.15.10.2509 GPU #2 Active: false GPU Accelerated Windows: 1/1 Direct3D 10 Vendor ID: 0x8086 WebGL Renderer: Google Inc. -- ANGLE (Intel(R) HD Graphics Direct3D9Ex vs_3_0 ps_3_0) windowLayerManagerRemote: false AzureCanvasBackend: direct2d AzureContentBackend: direct2d AzureFallbackCanvasBackend: cairo AzureSkiaAccelerated: 0

JavaScript

Incremental GC: true

Accessibility

Activated: false Prevent Accessibility: 0

Library Versions

NSPR Expected minimum version: 4.10.3 Version in use: 4.10.3

NSS Expected minimum version: 3.15.5 Basic ECC Version in use: 3.15.5 Basic ECC

NSSSMIME Expected minimum version: 3.15.5 Basic ECC Version in use: 3.15.5 Basic ECC

NSSSSL Expected minimum version: 3.15.5 Basic ECC Version in use: 3.15.5 Basic ECC

NSSUTIL Expected minimum version: 3.15.5 Version in use: 3.15.5

Ah! I see something!

Your troubleshooting information says that there is a user.js file in your Profile Folder

The user.js file is only present if you or other software has created it, so normally it wouldn't be there. The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file.

Delete a possible user.js file and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value including prefs set via user.js and prefs that are no longer supported in the current Firefox release.
You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Preferences_not_saved

Rename (or delete) the sessionstore.js file and possible sessionstore-##.js files with a number and sessionstore.bak in the Firefox profile folder.

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Multiple_profile_files_created

Thank you everyone for your help. Moses, your solution worked!