This is a Thunderbird forum. Are you actually asking about Thunderbird or really about Firefox? In both cases, the answer is pretty much the same; go to the site (below), drill down to the version you want, on the platform you use (windows/mac/linux), in the language you use, and download it, then run it. There is no need to uninstall the previous version. Thunderbird email: https://ftp.mozilla.org/pub/mozilla.org/thunderbird/releases/ Firefox browser: https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/ I think most "usability" issues with Thunderbird would be addressed by using TB v24.6. I'm not so sure what would have changed in Firefox to annoy you. ;-)