Dick,you don't say how you aim.
If you shoot instictive,try shooting POA or Split vision to get an idea of what your eye/arrow relationship is between both split finger and 3 under.
This should give you an idea of how to change your instinctive shot to compensate for that difference.
You can then return to purely instinctive shooting because you should now have a better understanding of the tradjectory change.
I shoot both split and 3 under with differant bows,but I use the same anchour point for both.
With 3 under I know I've lessened my arrow angle so it stands to reason I will shoot lower if I stay with my split point of aim.
Before you get all "instinctive is best" on me,,just consider the point of aim is simply the distance at which your arrow will impact if you place the arrow tip on the place you want it to land,,it's not a new old or any other form of aiming,it's just the knowlage of your bows performance,and a valuable tool you can use if you understand it.