Outdoor TV volume too low with DVD

[Sagecoachdriver]

We only used our 32" Jensen JE3212LED TV once to play a DVD of Long, Long Trailer with Lucille Ball which our friends brought on our campout. Volume on TV thru the antenna goes to 70 on the scale is is plenty loud. But when we play a DVD thru the Radio/ CD/DVD, the volume only goes to 40 and is way too low. We had to be right on top of the TV to hear it. Is there a way to make it louder? I see 2 speakers next to the radio and the 2 up by the awning which I guess are operate thru the dash radio. That's silly, you'd think they would have it coming from the outdoor TV and radio/cd/dvd player. In our bag of manuals was a small bag with lots of cables, perhaps a set goes from the Radio/CD/DVD audio to the TV. Any suggestions?
Also, do I really need to use one remote for the TV and the other to play the Radio/CD/DVD?

[Sagecoachdriver]

Played around with it this afternoon and found that if I move the fader which was in the middle to the rear, it gets a little louder. If I move the fader to the front, it gets lower volume. So this helped a little. I looked under the sofa where the sub-woofer is and just behind it is the plastic cover for the outdoor radio/cd/dvd. It has all likes of wires dangling with some on the floor next to the sub-woofer, all those wires can't possibly be for a simple setup from the radio to the TV. Perhaps, I can find the wires for the two outdoor speakers and hook them up to the radio for the fronts and use the fader????? Having those two outdoor speakers working off the dash radio is silly.