Hi Lily,
I’m not quite sure what you would be describing as hyper, because that really isn’t a typical cockatiel trait. I really need more information to be able to help you. Is he flying away from you when he is out? If so, maybe he needs to have his wings trimmed by a professional. He may be feeling a bit too independent, especially if you let him come and go from his cage whenever he wants to. Is he running from you in the cage and not coming out? In that case, something has caused him not to trust you. I’ll give you the links to our behavior and training pages and if you still need help understanding why he is behaving a certain way, please provide more details as to what the issue is.
Pet Bird and Parrot Behavior
Teaching Your Bird
Thank you for asking Lafeber,
Brenda