Do kings have to jump in the game of checkers?

You will find a variety of opinions on this issue.

The game is so old that one is hard pressed to find the "official" rules.

It's best to clarify the point about kings before starting a game with an opponent.

It's best to clarify the point about kings before starting a game with an opponent.
Here's a cool site -- http://www.jimloy.com/checkers/rules.htm

10. A King, once crowned, can move in any direction as the limits of the board permit. A King can "jump" in any direction one or more pieces, as the limits of the board permit. When a piece is not available for crowning, one must be furnished by the Referee.

[The phrase "any direction" means diagonally forward or backward. The phrase "as the limits of the board permit" merely means that you can't jump off the board. As I said in my comments concerning rule #2, a king can only jump diagonally over one adjacent piece at a time, in any of the four diagonal directions. Of course, multiple jumps are possible.]

Once your fingers touch one of your checkers, you have to move that piece, and can't switch to another one.

Agreed, Kings CAN jump (and move) forward OR backward... but it's up to the players on whether they MUST jump or not.

... like Euchre: Some people play "stick the dealer" and some don't. It's one of those things that is best to clarify before the game begins.