Do you only need to know what you changed from the default? After you customize using the UI, open the about:config page and check the box to show only the customized preferences. Of course, many of them will not be obvious, but here are some leads:

• "Clear history when Firefox closes" => privacy.sanitize.sanitizeOnShutdown, privacy.clearOnShutdown.*
• "Enhanced Tracking Protection" => privacy.trackingprotection.*
• "Do Not Track": privacy.donottrackheader.enabled
• "Delete cookies and site data when Firefox is closed" => network.cookie.lifetimePolicy
• "HTTPS Only mode" => dom.security.https_only_mode, dom.security.https_only_mode.*
• "Proxy" => network.proxy.type
• "DNS over HTTS" => network.trr.*

Thank you Sir! This information is very helpful! I still got a few questions, can totally understand if you dont have time to anser them all.

When i search for "privacy.sanitize.sanitizeOnShutdown" in about:config i find two results:

• privacy.sanitize.sanitizeOnShutdown • services.sync.prefs.sync.privacy.sanitize.sanitizeOnShutdown

Almost all of the settings you told me have two options, the one you shared and services.sync.prefs What exactly does services.sync.prefs do, and what happens if i set it to true or false?

When searching for privacy.clearOnShutdown in about:config there is a long list of settings Hopefully it's not asked to much if you can help me understand what those setting are? For exmaple i understand cookies,downloads,history,sitesettings. What are those: cache,sessions,offlineapps? I guess cache is like ram, a temporary storage? Session must be for how long i have firefox open counts as a session? Offlineapps i have no idea.

When searching for privacy.trackingprotection there are many results, some of them i dont understand what they mean. • privacy.trackingprotection.annotate_channels (annotate channels?) • privacy.trackingprotection.fingerprinting.enabled (there is resist fingerprinting, so what is this?) • privacy.trackingprotection.lower_network_priority (no idea what it does) • privacy.trackingprotection.origin_telemetry.enabled (no idea what it does) • privacy.trackingprotection.pbmode.enabled (no idea what it does) • privacy.trackingprotection.socialtracking.enabled (propably facebook etc?) • privacy.trackingprotection.testing.report_blocked_node (no idea what it does)

When searching for network.cookie.lifetimePolicy, the current value is set to 2 What other values can be used? What effect does value 2 and other have?

I have dom.security.https_only_mode set to true in firefox.cfg Just noticed there is more than just one setting regarding this option. Let me know which of those setting i should enable and which to ignore?

Please explain what are those settings? • dom.security.https_only_mode.upgrade_local • dom.security.https_only_mode.upgrade_onion • dom.security.https_only_mode_break_upgrade_downgrade_endless_loop • dom.security.https_only_mode_error_page_user_suggestions • dom.security.https_only_mode_ever_enabled_pbm • dom.security.https_only_mode_pbm • dom.security.https_only_mode_send_http_background_request • services.sync.prefs.sync.dom.security.https_only_mode • services.sync.prefs.sync.dom.security.https_only_mode_ever_enabled • services.sync.prefs.sync.dom.security.https_only_mode_ever_enabled_pbm • services.sync.prefs.sync.dom.security.https_only_mode_pbm

The setting "network.proxy.type" in about:config is set to value 5 for me. To be honest i am not using a proxy and i do not understand how a proxy works. I know how a vpn works. Should i change certain proxy settings so that they can benefit privacy while browsing?

DNS over HTTPS, network.trr.mode is set to value 2 so it's active. When i search for network.trr in about:config there is a huge list of settings. It's to much to ask what each setting does, but i will attach 2 screenshots below showing those settings. Besides "network.trr.mode" is there any other option here which i should edit when my goal is privacy? Also i am woondering, DoH's goal is to encrypt connections by using HTTPS protocol? If so, when i use "HTTPS Only Mode in all windows" what benefit do i get from also using DoH? Https only mode will already use https whenever possible so what exactly happens if i also use DNS over HTTPS? Im reading a documentation about DoH right now but still why not ask a professional at mozilla support.

The sync preferences control whether any customized setting syncs with the user's other installations of Firefox that are connected to the same Firefox Account. Many of these are only applicable to the same type of installation (desktop <==> desktop, but not desktop <==> mobile).

You can find information about what is stored in browser caches in help articles and Wikipedia.

I think "sessions" may be the preference corresponding to "Active Logins" in the dialog, and "offlineapps" may be the preference corresponding to "Offline Storage" in the dialog. You can open Settings and about:config in separate tabs to watch what turns on and off when you save changes in settings.

THIS THREAD IS NOT ADVICE ABOUT WHAT SETTINGS TO ADOPT.

Please use the interactive features to select the behavior you like, and if you find that there are additional or different things you want Firefox to do in relation to those features, ask about them individually. That keeps the threads manageable.

General Warning: Users that adopt a large slate of "privacy" settings in a config file without understanding what they do often find that Firefox stops working correctly on sites important to them, and they end up pulling out their hair in frustration or using another browser. Learn from their mistake and take it slow.

Thank again for your help.

Are you saying all sync settings are releated to firefox-account? Meaning if i do not use a firefox-account i can leave all sync settings on default, correct?

I understand that you are not giving me advice which setting to use or not use, i came with a specific question on how to manage firefox setting from about:config via firefox.cfg and your reply was extremly helpful for me.

If you mean by interactive features that i should edit the firefox setting by using the firefox settings icon, sadly those options are not enough for multiple reasons. I am currently experimenting alot with different operating systems and using firefox on all of them, it is time consuming doing the settings manually over and over so i rather use the cfg. Also firefox claims it is a privacy browser but at the same time comes with by default enabled telemtry which is a no-go for me. i am a bit worried about firefox's future but for the moment i will keep using it as long as my custom cfg can help improve privacy.

Question, is there any major or important difference between using a cfg to edit settings compared to if i would not use a cfg and manage all settings within firefox itself? Is there any difference at all?

Generally speaking, should my cfg break stability or cause any issues i will simply edit/remove the recently changed settings so that's not an issue for me.

I understand most of the settings which im currently using, i want to understand settings before deciding to use or not use them. that's also why i asked alot of questions. I will keep it manageable now.

I did try opening about:config and settings in seperate tabs at the same time and see what settings changes which config but i could only find out a few settings, it appears about:config has way more settings than the given basic-menu from firefox.

About dom-security there are 4 settings which i would like to know what they do. dom.security.https_only_mode_pbm dom.security.https_only_mode.upgrade_onion dom.security.https_only_mode.upgrade_local dom.security.https_only_mode_send_http_background_request

About privacy-tracking-protection there are 4 settings which i would like to know what they do. privacy.trackingprotection.lower_network_priority privacy.trackingprotection.testing.report_blocked_node privacy.trackingprotection.pbmode.enabled privacy.trackingprotection.annotate_channels Is this setting privacy.trackingprotection.fingerprinting.enabled releated to resist fingerprinting, how?

Question, what exactly does privacy.resistFingerprinting.letterboxing do?

Im using those two config settings: lockPref("browser.urlbar.placeholderName", "DuckDuckGo"); lockPref("browser.urlbar.placeholderName.private", "DuckDuckGo"); But still firefox by default uses google as search engine instead of duck, why? Which setting is responsible for the default search engine if not this?

You do not need to use Autoconfig to set preferences unless (A) you use a lot of profiles on the same computer, or (B) you want to lock preferences so they can't be changed. Otherwise, you can use a user.js file which has the same syntax as the prefs.js file and goes into the current profile folder. Firefox imports it at each startup, similarly to Autoconfig files. This site doesn't formally support user.js files, but you can search about them.

Generally speaking "pbm" indicates private browsing mode (private windows).

There are a lot of obscure preferences that either of us could research; this is the time I had. You can search in the source code of Firefox at https://searchfox.org/mozilla-release/source/ as well as using web searches.

Installed/visible/default search engine settings are stored in a compressed file named search.json.mozlz4 in your profile folder.