Youtube won't let me sign in. Let me explain. I was putting in my username and clicked Next or pressed enter. It just did nothing. Like it wouldn't let me sign in. I removed the cookies and cache and disabled anything that would be causing it but nothing works. But this only happens in Mozilla Firefox. Everywhere else is fine. Please help.
You could try a refresh of your browser, maybe something went wrong during an update. https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings
Before you go for that, you could also try to access/login the page in safe mode, if that works, it is more than likely that you can resolve your problem with refresh.