When I walk up to my bird's cage, and say "hey pretty bird" (or anything really) he opens his mouth and lunges at me with his whole body (but not leaving the perch) he will continue to do this as long as i talk to him. Why is he doing this?

idk

Was he socialized properly when he was younger?

Birds who are not accustomed to humans early in life will probably not be as social later on, and may try to defend himself out of fear if a human gets too close for comfort.

You are invading his territory. Getting him out and taking him away from his cage is OK, but that's his sanctuary and you are trespassing. If he's tame, he will probably stop doing that, but maybe not. Depends on him

Parrot breeder

Possibly a defense motion,or a threatening motion. Or it could mean he is glad to see you and wants your company. You have to learn the threatening signs. Wings sort of spread, tail flaired,eyes flashing. In my pionus case it means "Open the door . I want to come out and take a tour"