I am having some sound issues.  I have a 34 inch dell display with speakers and Logitech speakers with a subwoofer.   Both speakers have sound but it seems like they all play sound at different times.  What I mean is that there have been times when I get sound (flying 7337ngx) coming from both my monitor and my speakers.  Other flights, it only comes out of the monitor, other times it comes out of the speakers only.  Ideally I'd like everything to come out of the surround speakers and the monitor. However, when I pick the sound in the fmc to go to one speaker (surround Logitech) I lose the types of sound coming from the dell monitor.  Any thoughts?  I ask this because I don't have any AI traffic sound at all and I think that they are "programmed" to come out of the monitor.  Should I have one as default device and the other as a different setting (I can't select both as default).  Hopefully someone can point me in the right direction because I feel like I am missing out a bit. 

Is it just with the PMDG 737 that things change?  It has its own sound settings (what speakers/headphones are used) beyond p3d's sound settings.

It seems to be with all planes (however, I only fly the PMDG 737 and 777 at the moment with the new setup).  In the PMDG FMC< I have the sound set to my Hi Def surround speakers.  When I do that, it shuts off the sound coming from the monitor.  Yesterday, I had a flight and had both working well when I had the hi def speakers set as the default speaker and the monitor speaker as default communication.  However, when doing that, the audio coming back into my headset from ATC was gone and that was sent through the monitor.