Hi, i love doing replays, but i cant figure out how to straiten my back. My back is always leaning backward and i want it strait so i can land on my feet. Any tips how to straiten back?

you could try contracting abs

robbie i do that but then it doesnt do as much as i need it too

in what context of replay making? otherwise I would just tell you to keep your weight forward by bending or keeping your arms in front of you

try using your abs and lumbar, it may keep you on balance.
Make sure your glutes are in the right position or it won't work properly.
Be ware of what your joints are doing and keep them under control, these tips should make it easier for you to land.