yo, i used to have this problem all the time, and there's a few things you can do to fix it!
first, you can tuck it into your briefs/pants and use a belt and tighten it so it doesn't move up as much. i did that a lot in high school, mostly because i didn't have to move around too much besides gym.
second, you can pull the bottom half to cover your chest again so it binds twice as well! although it tens to slip if you pull it over, but if you pull it under itself, it stays even if you're moving around a lot
if you're want to compress your hips more with it, i suggest just investing in compression shorts. it's a lot less hassle then trying to keep your binder from rolling up all the time. also, your chest is more flat at the same time
hope this helped a bit!
-RJ