Can't sign in to YouTube account from mobile device after linking Google+ to it

Question

YouTube

In the morning I went to YouTube from a PC, a window popped up in which it said something like “you need to link accounts to your Google+ profile.” I agreed and watched a couple of videos.

Now at home I'm trying to log in to a YouTube account from a tablet using the McTube application and I see the message " Login failed. It looks like your Google account is not merged with your Youtube account ".

When I log in to YouTube from a PC, it now asks me which account I want to log into, supposedly I now have two of them, one old one with my last channel, all videos and subscriptions, and a new empty one to which hellish Google+ is attached. And most importantly, the empty one is a priority, and I think it is because of this that I now cannot log into the account from the tablet.

Has anyone had a similar problem and how did you overcome it?