Size problem via Youtube direct

Hello everybody,

When I share with my iPad, everything is fine. On the other hand, with zoom live via Youtube, the problem is that my screen, the size is small at the top and on the right. I looked everywhere to enlarge it, because I express in Sign Language, it is important that the public sees the screen better in large size.

Do you have any solutions to enlarge this size? Thank you for your help.

Yours sincerely