First: all parrots make some level of noise for a certain period of time, usually twice a day for maybe 15 minutes to an hour each time. It is natural and instinctive.
If you can't deal with that, then please rehome her.
If that's well understood of what having a parrot in the house entails, follow this checklist and solution.
First: does she have adequate and enriching time with you? A couple hours out of her cage everyday playing games, training, exercising, just hanging out and participating in 'flock' activities (eating, watching TV etc).
Second: is she medically healthy, eating nutritious food and getting enough sleep? Sick, malnourished or tired birds are more likely to be irritable and act up.
Third: does she have (from her perspective) an enriching and stimulating cage with plenty of perches, toys and things to do? Not just the same 3 toys in there day in and day out---but at least 6 toys rotated out for a new group (it's ok to hide 'last week's' toys for a while to make them like new again, but have four groups) every week. Is there treats and foraging toys and things to do?
Fourth: does she have a reasonably set (you don't want it to be too predictable as then she will become obsessed with sticking to it right down to the minute) schedule and routine? Can she expect certain things at certain times of the day? Chaos makes for insecure and nervous birds----she can't predict when she will see you again or what happens next.
Fifth: Is going back to her cage a positive thing (ie does she look forward to it because she knows you will have put a treat or something new for her to explore when she goes back)? Or is it going into the cage= isolation from you, lack of enrichment and boredom/less fun than being out of the cage
Six: have you responded to her screaming? If so, you've told her that 'if you scream/make that noise I will come and give you attention/respond to it in some way', which means she will keep using it to get what she wants (attention, being let out etc).
You need to ignore it. No matter what. Get earplugs if you have to. It will get worse (as she won't understand why it isn't working anymore at first so will get louder) before she gives up and stops making the noise.
Seven: the final piece of the puzzle is to give her an acceptable way to communicate with you. She is either asking for attention OR attempting to contact call you (to find out where you are---important to a parrot's sense of safety as they would use this in the wild to keep in touch with the other parrots). If you don't give her an appropriate way to fill that need she will continue to scream even if you ignore her because she doesn't know what else to do to try and fill that need.
How you do this is while you are ignoring what you don't want (screaming) you are also responding/giving her what she wants when she makes a noise you like.
Say she whistles or makes some other pleasant noise---answer her or give her attention.
She will soon learn what works to get her what she wants and what doesn't.
Some parrots are very needy, they can get "separation anxiety" desiring constant company. Adopting an older birds means your adopting whatever their problems. Not sure if your can calm an older bird, but good luck.
I'm just going to leave this here for you
I have a green cheeked conure named Juliet, and she is the sweetest bird ever. But when you her in her cage, she will squawk/scream every thirty seconds or so for hours at a time. I think she's doing it for attention, but we can't give it to her every second. She's almost five months old... it's not a young bird thing, is it? Like how puppies are crazy but then mellow out? Please tell me how we can keep her quiet. My parents say that if we can't find a way we'll have to get rid of her. I just can't do that- like I said, she's normally the sweetest thing thing. Please help me.
