On iOS, I'm not sure if this applies to all Apple products but it does on my iPad. When I open a sign and start writing on it once I go down to line 3 or 4 the 'x' close button goes off the screen therefore I can't close the sign and the only way to get off it is to have another player break it or leave the game without saving. My friend who plays it on a kindle had no problem with this because they have a back button on their device, a feature I don't think and Apple products have.