You will see the same complaint over in the Samsung forum. The maker blames the app authors. This is new ground for consumers where a TV has apps like Windows. You don't complain to Dell if an app fails (most of the time.)
In this case if LG can't fix it I strongly suggest you return the product.
I recently purchased and connected my LG TV (55LM7600) to my Denon AVR 1913 receiver, a Verizon FIOS TV HD DVR satellite box (by Motorola), and surround sound speakers (Energy Take Classic 5.1). I used HDMI cables to connect the TV and DVR to the receiver. I am using the wireless internet menu on my Smart TV application list to access Netflix, Youtube, etc.
When previewing these app's, I only get sound through the LG TV's speakers, yet I can still hear the television program I am watching off of my FIOS DVR through the surround sound. The audio stays with the show I am watching on TV but the video/what is showing on my TV is the applications.
I get sound through my surround sound the speakers when I watch TV or a DVD but not when I access the Smart Apps. Do I need to use a digital optical audio cable to fix the problem, if so why can't everything be ran through my HDMI cables. Any help would be greatly appreciated.