[Lori~D]

She was in fact being a normal Macaw. They do that on occasion. Mine will do that if he even Smells a hot wing in the house. Other than that he is normally fairly quiet. LOL, welcome to Macaw land. Your lucky to have a happy healthy bird if they do that once or twice a day for anywhere from 15 - 45 minutes. I cannot help myself to ask but did you not know this would happen?

"You have to ask yourself why is she screaming?
Is she bored? She's still new so is she feeling insecure? Is she calling for you? Did something scare her? Did something change in the room that she's not sure about? Has she gotten out of cage time today? Does she have destroyable toys that you can redirect her attention to?"

Is it possible she is just plain HAPPY? She is in fact a Macaw,lol. Have you ever heard them in the wild?
Oh and BTW - this is no offense I hope, it just made me giggle and YES Macaws do get loud during storms in the wild too!! Biting is always a possibility when a Macaw is excited and stimulated and it doesnt mean they are wanting to hurt you - you just dont have feather armor! They bite when excited and you have to learn when to let them be. Usually alwas when they are flapping and screaming!!
One thing you can try (works for me) is to walk up and start taking to them in a whisper. Have a whole conversation. They will shut up to listen to you. Then after they calm down you can redirect by moving to a different perch or giving a toy. I dont like to use food treats as it will encourage them to scream for it.