Try to make sure the area is fully dry before applying the diaper rash cream. Try different brand of creams? You can also try to do a proper butt wash (with running water) instead of using wipes - this is more tedious but I do this after every poop for my son and he never got a rash again. I also used to add breast milk to his bath to help his rash heal faster
We switched from pampers to huggies and that made a huge difference. We also use tubby Todd diaper cream and it's way thicker than others and helped too
We've been using the aveeno nappy cream and it's worked wonders for my little girl x