I too had this problem long ago when I got my X. If you notice when it asks you to enter your password it says
youryoutubename@youtube.com as if it is an e-mail. What I ended up doing, if I remember right, was go to settings->accounts and when in there i think it showed a youtube account. I removed that and then I had never had an issue again.
I won't be 100% sure being as it was like a month and a half ago, but try that