I agree with the above, though I call it the "Shunning Method", and there are several threads/posts that explain it in-detail. It important that everyone does the "Shunning Method" every single time he bites anyone, and that everyone in the room at the time it happens literally "turns their backs" to him and totally ignores him in every way for a full 5 minutes (no more, no less, as less time will not prove the point, more time and he'll lose interest)...
Birds hate being on the floor, as they are the lowest thing in the room, and their perceived dominance is taken away from them when they are on the floor. And the only thing they hate worse than that is being totally ignored or "shunned" in every way by "their person" or people. It's more involved than simply "ignoring" the bird when he bites, you literally must "shun" the bird completely and must literally "turn your backs" to the bird, and he must see you turn your backs to him. And if he tries to climb up your leg from the floor or fly to your shoulder, you don't say a word, you simply put him right back down on the floor and again turn your backs to him. You must keep your backs turned and not say a word for the full 5 minutes, and not respond in any way to his screaming or any other noises or calling. And leaving the room isn't really a good idea, as it's much more impactful if you stay in the same room as him with your backs continually turned to him so that he can visibly see that you are purposely "shunning" him...
So anytime your bird bites anyone, that person says whatever verbal cue you choose to say every time he bites, and it must be the same each time, something simple like "No Bites!" (be careful not to yell it at him, simply say it firmly to him in a normal tone of voice), then that person immediately puts him right down on the floor, then that person and everyone else in the room turns their back to the bird and stands there totally ignoring his existence. If he walks around to the front of you, you just turn your back to him again. If he crawls up your leg or flies to your head/shoulder, you immediately put him right back down on the floor and turn your backs to him again without saying a single word. You pretend like he doesn't exist, all the while "shunning" him with your backs to his face...And at the end of the 5 minutes it's important that you don't just go and pick him right back up or start talking to him again. Instead, at the end of the 5 minutes "shunning" period you simply start talking to each other again, or just move to a chair/couch, not saying anything to him, but instead let the bird come to you...At the end of the 5 minutes I typically just walk right to the couch or the nearest chair and pick up the TV remote or go back to whatever it was I was doing, and I don't say a word to the bird, I let them come to me, and when they do THEN I start treating them completely normally again, without referencing the biting again. You don't want the 5 minutes to be up and then you immediately turn around and look at him and start going "Awe, okay, I love you, etc.", because that kind of negates what you just did. Let him come to you and then just act like it never happened...
***It's pretty common that right after you do the "shunning method" and the 5 minutes is up, that the bird again just bites someone right away. If that happens, and it probably will, then you have to do the exact same thing again immediately. You again say "No Bites!", put him right down on the floor again, and turn your backs to him again for another 5 minutes...It's not unusual to have to do this 5-10 times in a row the first time you start doing it, and that is frustrating, but most birds will get it that very same day after you do it a few times in a row...I've actually had some birds who after I "shun" them for the first day 2-3 times in a row, they actually figure it out but want to "test it" to make sure that's what is going on, and so they'll bite me one more time in a curious, kind of inquisitive way, and I'll again say "No Bites!" and put them back on the floor, turn my back to them, the 5 minutes goes by, and then I'll go and sit down somewhere and they'll slink on back to me again and that's it...They get it. They hate being treated like they don't exist, they hate being the lowest thing in the room, and they are extremely intelligent. While a dog doesn't want to be "punished" so they learn not to do something, a parrot actually understands the concept that you're going to take something that they love the most away from them if they do a certain behavior.
***The "shunning method" should take care of the biting issue pretty quickly...However, you can't use it to try to curb the "screaming" issue...Now it's likely that his screaming and his biting are linked, and the biting is just the screaming not getting what he wants, so it then turns into a bite...However, with a bird who is constantly screaming when it comes to "their person" leaving the room, or being in the same room but not doing what they want them to do, you have to be extremely careful to not "reinforce" their screaming accidentally without being aware of it. You must be extremely conscious of your actions and be sure that you don't accidentally "reward" his screaming...
For example, if your bird is in a room and you walk out of the room, and he starts screaming, you absolutely cannot walk back into that room he's in until he totally stops screaming. If you do walk back into the room while he's screaming, then with his level of intelligence, you just taught him that "if I scream and scream and scream, eventually he'll come back". And most people don't do this correctly at all because they lose their patience and become frustrated due to the screaming and they just want it to stop,
so they eventually just go back in the room while the bird is still screaming, which you just cannot do...And yes, he might continue to scream for hours straight, but you just have to deal with it and "wait him out". And the best thing you can do is as soon as he stops screaming and you're sure that he's stopped screaming all-together (like he's not just taking a minute-long break to get a drink) then go back into the room to show him that screaming isn't going to get him anywhere, no matter how long he does it. And this applies to ANY and ALL reasons that cause him to scream because "he's not getting his way or what he wants". For example, if he starts screaming when you get in the shower (assuming that he's not in the bathroom with you when he starts screaming?), just take your shower and let him scream, don't end your shower early or rush it and then immediately go right back to him as soon as you're out of the shower. If he is in the bathroom with you and he is still screaming at you, seemingly because you are getting into the shower and you're going behind the shower curtain and he can no longer see you, do not talk to him continually while you're in the shower to reassure him that you're still there, because that will reinforce his screaming in other situations when you're not able to continually reassure him that you're there. He's going to apply the rule that "If I scream I will get his attention" to any and all situations, not just when you're in the shower where you are actually able to talk to him continually the entire time he can't see you. If he is in the bathroom while you're in the shower and he starts screaming when you close the shower curtain, just let him scream, don't talk to him UNLESS he stops screaming while your in the shower. There's a big difference between simply talking to your bird while you're in the shower and he's in the bathroom at the same time, and your bird screaming his head off as soon as you get in the shower and you continually reassuring him the entire time you're in the shower, with him continuing to scream the entire time you're trying to reassure him...Obviously that doesn't work to stop his screaming, because it's not what he wants. He doesn't want you to "continually reassure him that you're right there" even though you're behind the shower curtain, he wants you to get out of the shower and pay direct attention to him.