lyuan1,

I'm sorry to hear that you're having this problem with your television.

From the symptom you describe, it sounds like it's possible that it might be an issue with the volume button control. Check your remotes make sure that the button isn't stuck or pressed down in comparison to the other buttons. You might also try removing the batteries from the unit to see if the volume still goes down.

If it does still happen with the batteries out of the remote, you may need to contact the Samsung customer service center in your region. I'd recommend reaching out to them for troubleshooting, and if that doesn't work they may need to have a technician inspect your unit.

--HDTech