This worked for me. My audio had been set to leveling.
I had to get TCL to push an updated version of the software. The process took about a week and a few calls and emails to TCL, but it's been resolved.
Mine did the same thing the second day of purchase. I tried things from below and the one that worked for me was selecting settings on my satellite remote and selecting sound settings and cutting Dolby digital off!
Thank you, this worked for me. The beeping was freaking my dog out and she would no longer sit in the room with us. As soon as we did this and turned off leveling, everything worked great.
This simple fix eliminated annoying beeping noise changing cable channels on my new TCL TV.
Make sure it is on off on volume mode