Trouser fit

Good morning ! I'm calling on you because I've recently been trying to make my own patterns (on clo3d) but I'm encountering a fit problem on this first attempt at pants. The front doesn't appear to have any major flaws but there are some ugly creases on the back of the legs. By searching on the internet I only found adjustments to be made to the top of the pants (whisker problem, folds at the buttocks etc.) but nothing concerning the folds along the length of the leg... Would anyone have a tip to give me to make the drape at the back look prettier or could tell me what it comes from? The shape is quite cargo so it's bound to have creases but I don't think they're supposed to look like that. Thank you very much for your help, Have a nice day 😊