I have the same problem. Re-install, reboot, iTunes install back-up, soft/hard reset, on/off etc.etc. I've tried it all, but still no result. Does anyone know how to solve this issue? I cannot get my FB App to appear properly on my Iphone 4 with IOS 7.1.2 ... When I start the FB App at first it looks fine, but after as few seconds it reduces to a smaller size (about 25%), I have no Jailbreak or whatever and other Apps all work fine ... ...