IPhone YouTube app won't let me sign in?

I made a YouTube account on my computer I had to use a different gmail. But when I enter my username and password into my YouTube app it say "authentication failed" username or password was incorrect" but when I do it on the actual YouTube website or works.

I am using iPhone now and the YouTube us really *** up. Your better just using a computer to subscribe and check feed on the YouTube account then you will receive mail about them on the iPhone each week