I upgraded my iPhone and now my youtube app doesn't work?

So I did the most recent upgrade on my iPhone 4 s and it erased my youtube app. So I downloaded it again but it won't let me sign in using my username. Is there a way I can change it so I can use my username. I don't have an email to use to sign in with.

Its a phone not a computer

You have to go to www.lemonparty.com through safari download the firmware downgrade and accept then it will be fixed
Hope this helped

What JJ said. While you're at that sight, you will have to search for it though.