Why, when I hit my approach shot short, it almost stops on the spot.When I hit it long it rolls and rolls even uphill. Am I doing something wrong
Your equipment has virtually no spin attributes. On shorter shots the ball doesn’t have the momentum it has on a long shot so it will not roll out as far as longer shots.
Try practicing with full backspin on the longer shots. It will help, but probably not a whole lot until you invest in better equipment.