sight it in for the broadheads and dont worry about where your fieldpoints are hitting .
moving your rest around isnt going to help with your situation . I always walk back tune a broadhead, otherwise you will find your hitting right on at 20 and then it keep slowly creeping one way or the other at further distances. your other option is to find a differnt broadhead and try that , not all broadheads tune the same as field points , Closest for me was the slick tricks as far as hitting where a field point hits and those do massive damage for a fixed blade .