Welcome to BYC! Glad you decided to join our flock. You've received some good advice from drumstick diva and a good link from Kelsie2290. How many birds do you have and how many square feet is your coop? You should have a minimum of 4 sq. ft. per bird (more is better) and plenty of roosting bars that are higher than your nest boxes. If chickens feel overcrowded, they will start nesting elsewhere. Also, how long were they confined to the coop before you started letting them free range. Chickens need to be acclimated to the coop so (as drumstick diva said) they will think of the coop as home and safety. Please feel free to ask any other questions you may have. We are here to help in any way we can. Good luck in getting your flock to roost back in their coop.