Moving the dot up puts a little topspin on the ball, making it fly a little lower and roll a little more after the balls lands.
Moving the dot down puts some backspin on it ... ball flies higher and less roll.
In general, use some topspin when you shoot into the wind .. lower trajectory isn't as affected by the wind. With a good wind at your back, you hit it with some backspin... higher ball flight lets the wind carry your ball farther.