Welcome to the forum.
All advice on behavior issues is great, you never know what will click or work for you guys. And as I've had to deal with screaming birds before, you have my sympathy it can drive you nuts!
How old us Mango and how long have you had her, and lastly have you had parrots . before? What kind if parrot is mango?
First birds flock call, to keep them safe. If left unanswered they get worried and start calling more. So use the same words , ir whistle as yiu flock call. I have several burds , I would have used tge sane for all but I took in rescues and rehomed burds that already had a routine, so one us a wolf whistle, one is just kiss sounds, and one is " its ok" just idea for you. But birds like routines and rituals.
Ok, now it can take time and a multi prong approach to get tge screaming under control. Burds can scream from a lot of reasons, but usually their needs aren't getting met. All of tge scream burds I've gotten past the screaming have been from doing these things. Having them out if the cage and part if my life as much as possible, minimum 4-5 hours daily. Enrichment of their life abd getting them doing as many natural behaviors as possible, and making choices for themselves . I keep mine flighted. Tgey have access to a wide shallow dish ( I use a serving dish or brownies dish) with a couple of inches if water. So they can choose when to take a bath. My GCC takes a bath every day, my quakers take about 2 a week. Feeding a huge variety of veggies, leafy greens and just a few fruits in addition to their seeds and pellets. Also cooked beans, cooked quinoa, cooked oatmeal, boiled eggs. I rotate what I offer but usually 4 choices of these in the morning . They have lots if different types if things to shred and chew, foot toys, different perches and swings. The outside of the cage and in top of the cage I also have lots of rope and other perches . I use the space above the cage too! I out in ceiling hooks and use fishing line to hang rope spirals, hoops, swings so tgey are just a few inches above the cage. Parrots enjoy acting like monkeys, testing how far they can jump without flying, hanging upside down, climbing ect. Parrots are very social so they need hands on time too, for head scratches and cuddling. Doing all that usually drops the screaming by 80% right off the bat!
Then you work on postive reinforcement when quiet, treats and praise. Redirection when needed. Fixing any causes or stress that you find.
This is a good link, fir stressed or nit stressed parrot.
https://lafeber.com/pet-birds/stress-reduction-for-parrot-companions/
I will link another good article. In a minute
This one covers a lot of behavior and some problem behavior.
https://lafeber.com/pet-birds/bird-behavior/
