araquen solved it:
Okay, so I got Youtube to work. These are the steps I took
:1) I unlinked my YouTube account from my Gmail Account.2) I changed me email in my YouTube account to my gmail address.
3) I logged in to myYouTube account using my YouTube log in.
4) I linked my YouTube Account to my Gmail Account.
5) I logged into my YouTube app using my Gmail Account information.
I am not sure if this is the true fix, but my thought is that if I force everything to look at the same data, some part of the login process has simply got to stick.
I cannot guarantee that this will work consistently. My understanding is that most fixes that have popped up on the internet have been temporary at best. I also did not try logging in to an unlinked account.
I would say that the root cause of this issue is the kludgy link process between gmail and YouTube and the app’s inability to navigate the kludge. I may be wrong.
via Apple – Support – Discussions – Cant sign in to YouTube App ….
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