LG Tv problem with LG 5.1 surround sound (1 Viewer)

I have a lg tv (32lg30) connected to my lg home theater system LHB953 by an optical cable. When watching cable that supports 5.1 surround sound , it will not play on all 5 speakers. It only plays through the center speaker and the left and right speakers. When watching a dvd, the rear speakers are not playing nearly as loud as the center speaker. All the speaker levels are the same. Is there anything I need to change to get 5.1 surround sound through cable and increase the rear speakers?

The optical output on a tv is ONLY for getting 5.1 surround from local HD channels, via the built-in tuner, when using an antenna. If you want 5.1 surround from cable channels that support it, you need to run your optical cable from the cable box, to the surround receiver. Not from the tv. Tvs that will even pass audio at all that way, will downmix the 5.1 signal to 2.0, and send that to the receiver. The best you can hope for is Dolby Pro Logic II (simulated surround).

In the cable box setup menus, you need to set the audio output to "Dolby Digital". You also need to set the receiver's audio input to "Auto". Do these things and see if it doesn't sound a lot better.
Good luck!

When watching a dvd, the rear speakers are not playing nearly as loud as the center speaker.

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They generally won't. The rear speakers are used for effects and atmosphere, and often aren't doing anything at all. Except when sound effects are panning all around the soundstage, they are almost never as loud as the speakers that are carrying the dialogue and main music and effects tracks - and aren't intended to be. You've set the relative levels of your speakers to one another, but what they actually do is a function of the sound-mix on the disc. And as a rule, these do not emphasize the rear channels as much as the fronts. But by all means follow all the steps that Ed has outlined and see how things sound then.

Regards,

Joe