Some people may act bossy due to the others might not like the person they are talking too, or they are just naturally bossy and it's a habit they happen to have. Don't worry to much, but if the person who is acting bossy around the others is meant to be a good friend to you, ask him or her why are you do you act so bossy around others? I hope this helps, if not let me know.
Because they want to control someone in order to have a higher power for them and they will feel like a strong person in charge of being a leader but a great leader is a boss but not too bossy where it gets demanding and irritating.