Why does Firefox want to update to the most current version upon starting when I have already updated?

Question

Upon starting Firefox, often after starting or restarting my computer but sometimes after closing the Firefox browser(s) for a significant time, the program asks to update. Firefox asks this every time, and I have no idea how many times I have updated to the most recent browser version and I suspect the update is not saving correctly so the program is continually reverting to the last recent browser version.

Answer 1

There are no useragent prefs listed in the System Details List and extensions.lastAppVersion: 15.0.1 suggests also that you run Firefox 15.0.1.
Do a clean reinstall and delete the Firefox program folder before (re)installing a fresh copy of the current Firefox release.
Download a fresh Firefox copy and save the file to the desktop.
*Firefox 26: http://www.mozilla.org/en-US/firefox/all.html
if possible uninstall your current Firefox version to cleanup the Windows registry and settings in security software.
*Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you lose personal data like bookmarks and passwords from profiles of other Firefox versions.
Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.
*(32 bit Windows) "C:\Program Files\Mozilla Firefox\"
*(64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"
*It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
*http://kb.mozillazine.org/Uninstalling_Firefox
Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.
If you keep having problems then also create a new profile.
*http://kb.mozillazine.org/Profile_folder_-_Firefox
*http://kb.mozillazine.org/Profile_backup
*http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall