Hi Jay:

Sounds as though you have our PMA7000MS series (i.e. not the new PMA7000B).

There are two (Left and Right) screwdriver volume adjustments you can make,
you'll need to refer to the installation manual (located on our web site) to
determine which holes and what direction to turn the potentiometer to
increase/decrease the passengers volume.

Our new PMA7000B has a concentric knob allowing individual volume control from
the front panel of both the crew and the passengers.

Hope this helps!

Sincerely,
Mark