Seems like developer option.
See if your remote has an "info" button. And press it
Try to disable Developer options
Sir which brand i hav same issue . in my case panasonic . go to picture setting in constart press 7 time . system menu appear . then set into shop mode . tv will reset . actually its live tv app issue.
You will google for shop setting for tcl or you simply reset the tv.using menu
TV is in demonstration mode.
Try this.
Enter engineering menu
Reset shop TV Go to the engineer menu 6425 , service menu will popup Reset shop
Reset service menu Go to the engineer menu 1950 , reset all
Looks like you have one of the developer settings enabled.