The first thing I would recommend doing is checking the sound settings on your TV. Many TVs have EQ controls available for the sound that can be used to tweak the sound. I'd recommend turning any changes to this off so it is not affecting the sound from the soundbar.
In the sound settings, you will also likely see an option for the audio format the TV is using. You will want to make sure it is using one of PCM, Dolby Digital, or DTS. As these are the formats the soundbar supports you will get the best audio quality using these formats. If your TV has more than one of these as an option, try changing between them and see which sounds best to you!
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