Hello, The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: ''This will cause you to lose any Extensions, Open websites, and some Preferences.'' To Reset Firefox do the following: #Go to Firefox > Help > Troubleshooting Information. #Click the "Reset Firefox" button. #Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish. #Firefox will open with all factory defaults applied. Further information can be found in the [[Reset Firefox – easily fix most problems]] article. Did this fix your problems? Please report back to us! Thank you.

Try deleting the user.js file in your profile folder * https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save#w_user-js-file-overriding-preferences