It appears the only way to get attention is to make this a return issue if the maker fails to correct it.
Yes, the YouTube app is not from Samsung but Google. But at just 2 weeks old this is far too soon to let them off the hook.
Just 2 weeks ago) got a new Samsung 55" Class (54.6" Diag.) 4K Ultra HD Smart LED LCD TV UN55KU630DFXZA.
The Youtube app worked for the first 2 or 3 days, but now no longer does. All the other apps seem to work fine, at least the ones I've tried, such as Netflix an Amazon.
When I select the Youtube app, the YV screen goes dark and stays that way.