Ok...still unable to 'add account' (when clicking My channel) within the Youtube app...Keep getting a "There was a problem authenticating" message...tried a bunch of things including adding my google account under 'Account & Sync' in the main 'Settings', but nothing works...
However when i go to Youtube website via my browser & click on a video it gives me the option of the new Youtube App under 'Complete this action using' ...so i select it & set it as default & it is now perfect for my needs...