Some checkers sets have a crown on the back of the checkers, so you can just flip a piece over once it is crowned to designate it as the king.
To capture these checkers, the king would have to jump forwards and then backwards.
This would apply only if a king were doing a capture move that required it to change directions, such as if two checkers were lined up next to each other on dark squares in a horizontal line.
However, when a king is capturing checkers, it can move forward and backward on the same turn.
Kings can still only move one diagonal space at a time during a non-capture move.
The king can move forward and backward diagonally on the dark squares, so it's easier for king checkers to capture your opponent's checkers. To crown a checker and make it a king checker, simply place one of your own captured pieces on top of it. King your pieces when your checkers reach the end of your opponent's side.