It is possible that you were overdrawing the bow before. Not as common as underdrawing, but possible. If so, you may well increase your accuracy by shortening your draw.
Some people also feel they increase their accuracy at the tiny targets you sometimes see at tournaments that are placed at a 10-20' distance if they only draw maybe 2/3 normal draw. I've noticed the same thing myself, but I resist the temptation to do it because my mind is always looking for opportunities to short-draw, and I don't want to give it any excuses, even if they are legitimate ones.
But anyway, for normal shots at normal targets, as Arne says, you have an optimal draw length, that doesn't have anything to do with an arbitrary anchor position, and is based on your body being in correct alignment at full draw. You need to find out what that is, locate a convenient anchor for that draw length, and then stick with it.