Hello abstainless, if you have problem with update firefox the better way is to download and install the new version.

1. Download a copy of the latest firefox from http://www.mozilla.org/en-US/firefox/all.html

2. Trash the current Firefox application to do a clean install.

3. Install the version that you have downloaded.

Do not select to remove your personal data, your profile data is stored elsewhere in the Firefox Profile Folder, so you won't lose your bookmarks or other personal data.

see also: Installing Firefox on Mac

thank you

Actually, if you don't mind, I'd love to have some helpful information from you on why this update isn't installing. Would you like to work with me to gather some logs and see if there is a bug that's keeping Firefox form working? it should only take a few minutes.

One thing though before you answer, does it always do this or only for this release? Firefox 25 is throttled right so it will only update if you go to About Firefox. If it always won't update on it's own then I'd like to see your logs