Creepershader

When I start Minecraft Pe, the game turns into CreeperShader, I haven't buyd it. Somehow it makes the full version into the demo version, and the only way to fix these Problems, is too reinstall the game. But it only works 1 time. If you try to open the app an second time, the CreeperShader and the Demoversion are there again. Is there a way to fix this?