Renee is right. Whispering can sometimes work wonders.
Turning you back and ignoring unwanted behavior is also good.
But based on what you said, I want to add some suggestions.
Since you said you were new at it, you may not know that a
certain amount of loudness is something all bird owners have to
be willing to put up with. Under normal circumstances, we
usually only have to hear it early morning and about sundown.
That's when they do most of their calling in the wild. In the
A.M. to see if everyone made it through the night and at dusk
to call the flock back to the sleeping area. At my house,
those calls usually only last about 10-15 minutes. That's not
to say they won't call to you at other times during the day.
It's just that us with Macaws have to deal with higher decibel
settings than most. On the other hand, if it's excessive and
at all times during the day, and especially if at night, then
there may be a health issue going on. If you are experiencing
that, then you really should have any possible health issue
ruled out first by a check up with a good Avian vet. It is
useless and just more frustrating for you and the bird, to try
approaching it from a behaviorial standpoint until you know for
a fact it's not health related. Hope this helps.