Needing help fast with my blue and gold macaw

[cornett12]

I have a 4-6 year old macaw that I have just bought a few days ago. Her previous owners locked her in a cage outside with a much older male scarlet macaw. She's made a big improvement since we first got her, she may well of been wild because they never really interacted with her but anyway she bites and screams when someone try's to touch her or hold her. Just in a few days she has let me touch her foot a little bit before she tried to bite and she take things from
My hand very gentle for a while before she eventually bites me. I'm just worried I will never get her to let me pick her up and play with her. I'm just looking for anyone who can give me advice on what to do to gain her trust and if she will ever come around and let me play with her. She's my first macaw and first agressive bird I've ever owned.