just don’t yell at him. my kids got 50’s 2 yrs ago. one was 5 the other was 6. i yelled at my youngest while trying to teach him to just go fast enough to balance. he fell over and refuses to ride it saying he wants a quad. my oldest is on a kx65 now.
you said it’s a honda 50, so it should be a 3spd autoclutch. just put it in first, and don’t let him shift it yet. that will restrict speed some.