Changing user iPad user name

Just bought a New iPad for my wife. When I bought it at the Apple store; a representative there helped me set it up. Problem that my wife has now; is that everything on the iPad refers to me. She plays games a lot; and every time she goes to a game; it will say; Welcome back “My username”! She does not like that and I don’t blame her. I have searched through all the settings and I don’t see where I can modify that information. Will someone please point me in the right direction?

Thanks; I’ll give those suggestions a try.