It might be too late to train this person that you don't have to turn off the AGC to get a preamp on
for use when on 20m and higher.
I am forever finding (on my W7 32bit servers) somebody leaving behind the following settings:
AGC OFF
Preamp ON
Visual Gain +30dB
Sometimes I even find the ATT on too.

On the 20M band, this leaves the radio with a -90-dBm (S-6) noise floor. WTFO?
Here's the pop up that appears when hovering over the Preamp button: