The points Grey Mare makes about roosters changing temperament as they come into their hormones are good ones. They are complex critters as they begin to grapple with the sudden influx of hormones.
If you could get into the head of a young cockerel as he emerges from chickhood into a new world of seeing hens in a new and complicated way, it would probably be a lot like what human boys struggle with as they hit puberty. Make no mistake, a lot is going on in their little boy-bird brains.
It would be: Sex, excitement, fear, sex, mistrust, sex, excitement, confusion,sex, food, sex, fear, sex, sex, sex.
A young cockerel is on edge all the time, taking in a lot of new information that is suddenly important, where as a chick, he took it all for granted. Now, everything seems to be HIS problem to deal with. Enter you, one day, into this new world of his. You're just filling the feeder, and you make a sudden move that he wasn't prepared for, and you find your hand now has a hole drilled neatly into it by his powerful beak.
For most cockerels, the next thing happening is he's suddenly dinner.
If the young cockerel who has made a mistake has a patient, understanding care taker, he'll be given another chance, and the caretaker will take into account his edginess when in his vicinity, understanding that this is generally a temporary thing for the next six months to a year, as the hormones level out and the young man learns to deal with his role in the flock and his relationships with his humans.
You can help him get through this rocky period in his life by modifying your own behavior and keeping boisterous, unruly children away from him. It's a good idea to behave with deliberate, slow movements, and try to keep things as calm as possible. When he does misbehave, he needs firm discipline so he comes to know his boundaries. But he needs to know that he can trust you and not be fearful of you. BYC has many excellent tutorials on how to discipline a young cockerel.
If you have a young roo who has suddenly become a problem, instead of asking why he's acting that way, if you can ask yourself what it is about your own behavior that has made him suddenly not trust you, many young cockerels might be able to live beyond that first turbulent year without becoming soup.