What...you could not hear her over there?
I will ask her to scream louder!!

(just kidding of course)
It takes some getting used to- and you can influence when they scream to some extent.
There is a couple in NL that have about 12 macaws in the house - and their goldfish makes more noise!
They have been trained not to scream for attention (and can all see each other, so why bother?), and sometimes they will have a guest -> that gets "told" by the flock "to just be quiet".
Screaming is their contactcall- so I have been (& am) training her to use "hello?" instead. She came here being taught to scream for attention- ignoring that takes a little practice, I can tell you!
Every time I slip up and react to a test-yell she wil get noisyer and if I keep it consistent she usually shifts more towards "hello?" and "may I help you?" (she has been in a shop for some time I think, she sound like quite the assistant).
So it is very much trainable.
(she does *not* yell at sunrise or sunset -> you always read about them doing)
She will yell 5 times if the phone rings or someone is in front of my door/window (really deafening if you stand too close), or use a single contactcall if she hears me outside.
My neigbours assure me she really is calling less and less, and that it does not bother them.
(I check sometimes with them if she yells when I am out, but that is a negative. HUGE relief on that one!)
If she really yells you can easily hear her half a block/street away.
(Not nice.)
Keeping her quiet when I come home late from danceclass or visiting friends is a challenge in itself. (all the parrots are in the livingroom and I have to cross it)
But we are working on it.