As for the 32LH510U...doesn't look like it even has the headphone jack, so it's pretty much the built-in speakers or nothing when it comes to sound. The only way you're going to be able to get the sound to go to the speakers is if the signal is coming from an external device (DVD player, cable box, etc.), & you send it through the sound system. You might be able to do it 1 of 2 ways:
1. Using component (Red/Blue/Green/Red/White), you could send the audio (paired Red/White) to the speakers & the video (Red/Blue/Green) to the TV.
2. Using HDMI, you'd have to send it from the device to some sort of receiver unit, then have the receiver send the full signal via HDMI to the TV set & send the audio by its connection to the speakers.