I am going to be honest with you here and tell you to forget about the 40 yard pin and farther for now.Take your 20 yard pin,fine tune it till the arrows are hitting where you want them(arrow hits high,raise the pin,arrow hit low,lower the pin,etc)
Practice makes perfect and dont have anyone else set the bow for you,its a personal thing and once your form is correct and the pin is hitting where you want consistently then practice at 30-40 and farther if desired