Replying to Popping from the hips... backflip help.

So I have looked at a lot of backflip threads to try to improve mine/make them more stylish and clean and one thing I have noticed is that everyone says it’s more of a pop with your hips and shoulders instead of your feet but I’m not exactly sure what people mean by this. I’ve done a lot of backflips and can lay them out on the trampoline but for some reason it’s hard for me to do it on skis, my arms always flail in the air and I noticed in videos I set the truck more with my legs rather then my upper body, any tips on how to fix this? Like what should my upper body be doing for me to set it with my hips?