I can't think of a setting to alert you... Firefox has 3 different configuration files where a home page can be set: * prefs.js - this stores what you enter from Firefox's Options dialog * user.js - this file is used to override your previous session settings at startup; seldom used by actual humans, but sometimes created by third party software to force changes to your configuration * mozilla.cfg - systemwide lock file to prevent Firefox users from changing the centrally prescribed home page (used by companies, but possibly hijacked by third party software) In addition to these settings, an extension could override the saved URL and show or redirect you to a different page. I suggest starting with a review of your extensions. On the following tab, disable ALL nonessential or unrecognized extensions: orange Firefox button (or Tools menu) > Add-ons > ''in the left column, click'' Extensions Usually a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step. You also can check for a user.js file using the steps in this article: [[How to fix preferences that won't save]]. Can you track down the culprit behind the changes?

*BrowserProtect: https://addons.mozilla.org/firefox/addon/browserprotect/