In level 15 where the runic is, crouch and there's a hidden wall. In level 13 if you go to the area across the jump with 4 red gems, theres a hidden wall to flat crouch through at the end. In level candy where you find the 2 spiders on a floating platform jump onto the left rope and hop into a wall near top corner of that area. And to get level 3 you need previous 3 saved first, than go back and finish it but once in chest area hop on chest and go through a wall, might have to jump through 🫡🫡