Extensions are options you install into Firefox, They can be removed at will. Plugins are from programs that Firefox finds already on your system. The only way to remove a plugin is to remove its program from your system. Is there a Remove button on those add-ons? If not, then it is a plugin. -------------- '''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.