Do you have the Sceptre X322BV?
Next how are you connecting the TV to the stereo? If you are using an HDMI cable and are trying to use the ARC (audio return channel) between the TV and the receiver/sound system, you need to enable the feature. Make sure that you have connected the HDMI cable to the HDMI 1 input (bottom of the right side inputs) on the X322BV. Press Menu on the remote. Navigate to the Setup menu and enter the section. Go to the CEC line and enter this part of the menu. Set Audio Receiver to On.
If you are using the SPDIF (optical digital output), first make sure that you haven't connected the audio cable to another RCA jack on the TV by accident. The SPDIF is the lowest jack on the left. The other RCA inputs are audio in, not audio out. Next go to the Sound menu. Go to the Other Settings section. Turn the TV speakers Off. You should check the digital audio modes that the stereo accepts. Then adjust the digital audio output (on the next line of the Other Settings section) to the appropriate mode. PCM is the one used by many systems; my surround sound system needs to be on MCM (multi-channel stereo mode). If you are using the headphone jack (top right side of the TV), try turning off the TV speakers as well.
The manual for the X322BV is available on the product support page: https://www.sceptre.com/productSupports-425.html#support
. The direct link to the manual is https://www.sceptre.com/pub/Manuals/LEDHDTV/X322BV-SR-User%20Manual.pdf
I hope this helps.