You could use the "Panorama/Group Tabs" (Use Tab Groups to organize a lot of tabs) feature to sort your tabs into different groups in order to have the more organized. For the most frequently used sites you can use "AppTabs"(What are App Tabs?) Or you could simply close some of the rarely used tabs (Maybe save them as a Bookmark (Bookmarks in Firefox) to find them again later).

But this doesn't really solve the problem. First I have to ask if you are using "Tabs on top"? (On the menu bar, click on the View menu, go down to Toolbars and tell me whether "Tabs on Top" is checked or not). Then: How many tabs do you have? Firefox does only show the vertical scrolling arrows when they are needed. How many tabs you can have without the arrows appearing depends on the width of your window, so could you please make a screenshot of your Firefox window and upload it here? If you don't know how to take screenshots: Add images and screenshots to Knowledge Base articles (just follow steps 2 to 8) and then add it blow your post . :)

Are you talking about tabs on the tab bar that shows the currently open web pages or bookmarks on the Bookmarks Toolbar?

• https://support.mozilla.org/kb/how-do-i-use-bookmarks
• https://support.mozilla.org/kb/Deleting+Bookmarks

The second answer revealed what the problem was. I was confusing the Bookmarks toolbar for the Tabs toolbar. Thanks.