I am a stickler for correct throwing. One of my new students just couldn’t get it right. I had recently been through this, with a 9 yo boy. I tried patiently demonstrating, coaching and using gadgets.
So, with this girl, I assigned her friend to keep encouraging her to get her arm up and not push the ball.
One day, I had my player reach up and try to swat a rag hanging from a pole, as she threw. It was somewhat successful. But, then, I thought - try throwing over the pole. Success. She still has a ways to go, but her throw is so much better.