Hey gang Tonight I shot a dozen times with the same arrow and 3 fletch all kill zone but slightly crooked into the target. Took the 3 fletch off and put 4 fletch on another dozen arrows shot SAME arrow shaft. You could have put alevel on the arrow sticking out of the target with the 4 fletch. Is this normal, luck , a fluke

If you have the proper spine shaft, it should make no difference. Your shaft is probably slightly stiff and the 4 fletch straightens it out a little quicker.
Could also be how you have the nock aligned. Maybe the feathers are hitting the riser on one or the other.