How bad would you say the fighting is? Unless they are drawing mild amounts of blood, making wounds, or going for the eyes, it's just normal pecking order behavior. They are just coming of lay and that changes up the order a bit. It's also very normal for them to assert themselves for a favorite spot to roost. They sound fine to me.
I agree with the last commenter. It sounds like they are not roosting on a roost? If they are on the ground, you should put them on a roost every night (unless it's a breed known for not roosting in which case ignore me). Chicks should actually have a roost available from week two. They are losing out on the development of very important roosting muscles. You are their mother hen and it's critical for you to teach them to roost at some point. While some do learn on their own to roost. Others need a bit of a push.