up towards the 20 yard pin.... if you move the sights up to the top, then you have to lower the bow to shoot the same spot. If you drop the sights down lower, then you have to raise the bow, thus shooting higher to hit the same spot.

Trying put the gap between the 20 and 30 on the bullseye and see where it hits. That will give you an idea of where to move the 30 yard up to.