Firefox says up to date but it is not (websites say firefox outdated)

Probably your UserAgent string in Firefox is messed up by another program that you installed. 

Please type about:config in the URL bar and hit Enter If you see the warning, you can confirm that you want to access that page. Search for general.useragent. Right click the preferences that are bold, one line at a time, and select Reset. Then restart Firefox.

or
https://support.mozilla.org/en-US/kb/websites-say-firefox-outdated-or-incompatible