when you use the refresh feature in Firefox then a new profile is created and some personal data (bookmarks and history, Form Data, tabs) is automatically imported. The current Firefox profile folder will be moved to an "Old Firefox Data" folder on the desktop. Installed extensions and other customizations (toolbars, prefs) that you have made are lost and need to be redone. *https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings