At 14U, we trust the catcher and SS to make the right play. They usually get the out. If the runner at third takes a chance to score, we usually get him too. Early in the game, get the guy at second. Later in the game, score and situation decides the play. There are no set signals. They decide based on what they think they can get out. If the coach has a priority, he yells it out from the dugout. I am not sure if opposing coaches think our guys are trying to trick them or what, but the coaches trust the kids ability to make a play.