Yeah, what you said, Nan. I agree that positive reinforcement works over negative hands down. I've found that a good way to discourage inappropriate behavior in a bird who craves your attention is to turn your back on it for a moment until the behavior ceases (like screaming) or after taking a nip. Morgan hates to have me give her the "cold shoulder" after she gets too rowdy and pinches. Being a flock animal, it apparently sends the signal "I do not consider you in my flock" when you turn your back. I can't take credit for that, Ms Twiggy is the mistress of cold shoulders when she's not pleased. Imitation is the sincerest form of flattery.
A lot of what I've found works for behavior modification has come from the first few months living with Ms Morgan. All my others kinda grew up together, her being an outsider it took some serious manipulating to integrate her into the flock. Another great way I found was the Irene Pepperberg/Alex "model/rival" technique, only since I was not working on speech but behavior, I used another flockmember. For example, screaming. If Ms Morgan was screaming, and the rest were quiet...I'd give them a treat and not her. Then....as soon as she was quiet, I'd give her one. Model/rival only works with multiple bird households, unless you've got a family member willing to play the part of "good flockmate".
I spend a little over 3 hours a night with my flock, one-on-one time with each one, and of course interaction with all of them. If one calls me, I answer. If somebirdie says "commere", I go see them for a moment. Nobirdie gets ignored, and they all are pretty good about waiting their turns out. And this is not just take out and put on a playstand action, either. I'm expected to play interactive games, or sing, or dance, or otherwise become part of a play experience. We all get exercise, and we all look forward to our special time together. The only downside to playing like this is I can only have one at a time out. Jealousy rears it's ugly head otherwise and injuries would be the result. But hey, what else do I have to do in the evenings?