on my wife's iPhone SE, her passcode is a 4 digit code but on my iPhone SE I was only given the option to enter at least 6 characters, how do I make mine 4 digits also?
When you create the passcode, it will ask for six numbers, but you'll see just above the keypad a tappable control "Passcode options". Tap that and you can choose a 4 digit passcode. (I'm not sure why you would; 6 digit is a lot more secure.)