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.

Sometimes it's not a problem with a stubborn setting, but some kind of malicious software. Here's my suggested procedure for tracking down and cleaning up bad add-ons and other hijackers. I know it seems long, but it's really not that bad. <p>(1) Open the Windows <strong>Control Panel</strong>, Uninstall a Program.</p> <p>After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. <em>Be suspicious of everything you do not recognize/remember, as malware often uses important or innocent sounding names to discourage you from removing it.</em></p> <p>Take out as much trash as possible here. If you're not sure, feel free to post program names or a screenshot of the list.</p> <p>(2) Open Firefox's <strong>Add-ons page</strong> using either:</p> <ul> <li>Ctrl+Shift+a (Mac: Command+Shift+a)</li> <li>"3-bar" menu button (or Tools menu) &gt; Add-ons</li> <li>in the Windows "Run" dialog, type or paste<br>firefox.exe "about:addons"</li> </ul> <p>In the left column, click <strong>Extensions</strong>. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions. <em>All extensions are optional; the troublemaker might not be obvious from its name.</em></p> <p>Any improvement?</p> <p>(3) You can search for remaining issues with the <strong>scanning/cleaning tools</strong> listed in this support article: [[Troubleshoot Firefox issues caused by malware]]. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case.</p> Hopefully that will flush anything on your system and in your Firefox that could be a problem, and you can regain control of your home page setting. Finally, a problem some users encounter is that the shortcut they use to start Firefox has been modified to load a specific page. This is separate from your home page setting and may not be an issue for you.