Android/iOS: Sometimes when you show pictures to a friend or relative, they start rudely swiping to other pictures. We have a hack for that. But what if they start opening other apps? Good Lord! I was shocked to hear people do this. But you can stop them. Here's how to enable the Guided Access shortcut and easily lock people into one app when they borrow your phone. You can even use it to entirely freeze your phone on one screen.