Crashes on iPhone version below 5s and iPad below Air

Hello, I realy need help! I am beginner in Unity. I made an app (only used UI, image, UI text) It looks like It good works on iPhone 5s iPad Air and above but does't work on iPhone 5c, 4s/iPad version below Air! On the old device you can see first scene (language select) and after you choose language you can see Loading scene and CRASH! In Xcode (when I build simulator SDK in Unity) I can not select iPhone 5c, 4s/iPad version below Air simulators, it is not avalible. On the scenes I use set active to unable and disable screens. May be problem with RAM but why iPhone 5c and 5 doesn't work. Please help me! Thank you!!!