These birds are bright and you have to treat them as you would a young child. They need a lot of mental stimulation as well as physical and this is difficult when trapped in a cage. As they grow they mature and have certain wants and needs.
You can try to increase the enrichment of his environment and there are lots of different puzzle toys you can buy and these will need changing around every couple of days so he doesn’t get bored. You don't have to keep buying new ones but rotate them.
Try hiding food around them house when he is out of his cage so he has to think about finding it and involve him in activities.
Perhaps allow him access to talk to other birds.
If this is not enough for your bird and he start plucking out feathers and won’t stop screeching perhaps he needs to be in an environment more suited to his needs as a bird that would normally hunt and search for food over large areas and have lots of other birds around him. Find out about how these birds live in the wild and ask yourself can I give him all that?
We often don't realise how much attention and looking after these types of birds actually need and I feel that they should not be stopped behaving as they would in the wild and do what birds do and that’s fly.
All the best
Rosie Barclay