What you need to understand if you want to change an autistic person’s behavior

If you want to change an autistic person's behavior, you need to start by asking yourself why.

If the answer has more to do with you than it does them, that's a problem.

If it truly is about them, ask yourself why it's important to them. (Not FOR them, TO them.)

If you can't explain it in a way that will make the autistic person INTRINSICALLY motivated to do the thing (because it fully aligns with their ACTUAL NEEDS)...

You're either wrong about it being an actual need, or you need to keep working on your explanation.