Here is what I do first. On the ground with the engine off. Radio on. give him the airplane. While he has it check the pressure of his thumb on the sticks. With your thumb go right over the top of his or reach over and see if you can tap the stick from his thumb if you can't he is putting to much pressure on the stick. He may have a case of "heavy hands" and then the nerves do not respond well. If he cramps up he is holding to tight. then what you have to do is get him to lighten the grip and pressure on the TX and sticks. Teach him the "Feel" of the TX and sticks.

If in the air let the plane stall. He has to learn what to do anyway. sounds like you are taking it back to quick. As long as you have a safe margin of error let the students make mistakes that is how they learn. Every person learns at their own rate. Let him get a scare or two. he will learn. Then you take the plane back and tell him to take a couple of real deep breaths and calm down while you reposition the airplane. then give it back to him when he is ready.

I generally will not take an airplane back until it is below treetop level. First flights are done high. Altitude is your friend.

Be patient every student is different. Find the problem and correct it. The buddy box may be a click or two out of trim might have been bumped. As instructor it is your job to find out WHY he is doing what he is doing and correct it.