How to fix preferences that won't save

Thanks for replying, but it says that if there is no user.js file, these steps won't help, and sure enough, there isn't any user.js file. And I don't want to reset Firefox because redoing the settings for all my add-ons would be more of a pain than these particular preferences not saving. Isn't there any other way to get it to work?

You can check for problems with the localstore.rdf file.

• http://kb.mozillazine.org/Corrupt_localstore.rdf

It still didn't work. There's another file called localstore-safe.rdf; should I have deleted that one too?

The localstore-safe.rdf is used when you start Firefox in Safe mode and there is usually no need to delete this file.

Did you try to redo the toolbar customization and did you keep it this time?

Can you attach a screenshot of the issues with Gmail if you still have them?

Reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• Press and hold Shift and left-click the Reload button.
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (MAC)

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Create a new profile as a test to check if your current profile is causing the problems.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer some files from an existing profile to the new profile, but be careful not to copy corrupted files.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

I removed the localstore.rdf file, which undid my customizations. I redid them but when I restarted Firefox I still had the same problem as I did before - the separators in the navigation toolbar disappearing (all the other customizations did save properly).

Maybe I should mention that the customizations have been saving properly in one window, but not in the others. But even when I tried getting rid of all but one window and then restarting Firefox, when I opened a new window the separators would be gone again.

I'll try creating a new profile to see if that helps. Oh, and the problems with Gmail went away on their own after a while.

You may not be seeing the separators as they maybe too faint with the Firefox or Windows theme that you use.

Did you check that by reopening the Customize window?

No, they show up fine in the bookmarks toolbar, just not in the navigation toolbar. However, creating a new profile did solve the problem, so I guess I'll see about transferring my files over to the new profile. Thanks for all your help. :)