Multiplayer: fix the controllers and incorrect keys.

A quick tutorial to show how to fix the issue if you can't play with 3 players, or if the keys are not correct in-game. Simple, quick, and effective.

(If the controller issue persists and you're having trouble controlling the players with the controller, it's probably because your controller is number 3 or higher. In this case, you need a tool to reassign the controller or restart your device and connect the controllers in order.)