Xbox one - can't switch accounts or open youtube

Hi,

I am having two problems with my sons Xbox one.

First, when he tries to open the YouTube app, he gets told that "the app is rated above your content restrictions" and he can not open the app to watch videos. This did not happen before e.g. 10 days ago when he last used his Xbox.

Second problem, is that if he logs out I cannot login with my parent account. I can choose my account from the left hand side, the screen goes a little dark but the pass key page doesn't show it simply returns me to the home page.

Has anyone any advice on how to resolve either of these issues?

Thanks