Yamaha RX-V620 Receiver "sound tv goes during commercials" Questions

...sound again when the program is back on. I tried 2 different cables to troubleshoot, and also hooked directly to my TV--when the HDMI was hooked direct to the TV--no problems, which lead me to ...

sound goes up from tv show to commercial When watching primarily HD programs the sound will often times increase dramatically when the commercial comes on. I need to turn it down then turn up the ...