Hi, You can try to set '''browser.warnOnQuit''' to '''false''' in [http://kb.mozillazine.org/About:config about:config]. [http://kb.mozillazine.org/About:config_entries about:config Entries] The [https://services.addons.mozilla.org/en-US/firefox/discovery/addon/config-descriptions/ Config Descriptions] add-on adds helpful source comments in about:config. If problems persist, you can reset Firefox and set the above preference. 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!

If you do not keep changes after a restart then see: *http://kb.mozillazine.org/Preferences_not_saved