How did you remove it? Type '''about:addons'''<enter> in the address bar to open your Add-ons Manager. Hot key; '''<Control> ''(Mac=<Command>)'' <Shift> A) ''' In the Add-ons Manager, on the left, select '''Extensions. ''' Remove “ modem booster or inkline “ '''Anything. ''' Also look for SafeSearch or SearchAssist Incognito. Now do the same in the computer’s '''Programs Folder. ''' '''Windows:''' Start > Control Panel > Uninstall Programs. '''Mac:''' Open the '''Applications''' folder. '''Linux:''' Check your user manual. ------------------ https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save '''Note:''' Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.