If your firfox will not update, due to the fact that “administrator disabled updates” message, you can enable this with:

• open regedit

• go to HKLM\Software\Policies\Mozilla\Firefox\DisableAppUpdate
• set key to 0 (1 means disabled)

• go to HKCU\Software\Policies\Mozilla\Firefox\
• check if there is a similar key present and change the value

• close / end firefox and reload

Link: https://support.mozilla.org/de/questions/1347191