How do you get the receiver volume and tv volume to stop working together at the same time?

It sounds like your TV is responding to the Denon remote. There may not be any way to stop it. I would just turn off the TV speakers and use the ones connected to the receiver. If you're using the TV speakers to make up for the lack of a center channel speaker on your receiver, it may be time to consider buying a good center channel speaker. The speakers provided in most modern flat panel TV's aren't very robust. The whole idea of having a receiver is to:

1. allow switching between various sources while using only one HDMI cable to connect to the TV.

2. Take advantage of surround sound in the 5.1, 7.1 channel mode receivers provide. When you have a good receiver connected to quality speakers and a good subwoofer you can really experience the music and sounds in a home theater environment.