I found it, it was off by default and I turned it on. I only watched two commercials and I can't tell if it's working or not, the volume stayed steady but I'll know more tomorrow.
THANK YOU! Yamaha is great!
Adaptive DRC as described in the Surround Realism section:
"Adaptive DRC (Dynamic Range Control) is a new volume control technology that is effective for low volume listening, such as at night or with headphones. It applies DRC processing to eliminate the volume differences between loud commercials and ordinary programming and to take into account our ears’ loss of sensitivity as volume decreases. The compensation is performed automatically, so all dialogue is heard clearly even at low levels, and there are no sudden loud bursts of sound."