Is there any way to override the 950's auto audio selection?

If I'm watching MTV, VH1, whatever music channel, with Time Warner HD cable, I'm forced to use either Stereo, or Pro Logic modes. None of these are putting out sub signals to my sub amp.

I *want* to use 5 or 7 channel stereo, but, it's not available.

Whats the deal?

Inputs are coming from a digital coax cable, and the 950 seems to select every audio program properly as to what I'm watching, but, dang it, I want something else.

Thanks for any input.