Maybe try to fold a towel and place it under the back of the saddle so it doesn’t move up and down
Try something like a pad with padding towards the wither to drop the saddle back onto the horses back so it won’t bounce.
Mayberry you could try a riser or a half pad.
Hi Alannah, you can maybe try a withers pad, but you have to make sure the saddle is not too tight for that 😕