Just bought a new Samsung 40" UHDTV (UN40MU6290F) from Walmart. Got it up and running, and it's beautiful. But I've hit a snag. I'm ashamed to say that I can't figure out how to turn Closed Captions on. I found "Caption Settings" under Settings-->General-->Accessibility, and set it to ON, and Caption Mode under it to "Default" (I tried all the other settings as well). But no captions. I don't know what else to do. I am 67 and my hearing is not what it used to be. I used CC regularly on my old TV. This TV is visually lovely, but will not be of much use to me w/o CC. I must be missing something, or doing something wrong...I cannot imagine that a top-of-the-line 2017 UHD TV doesn't support CC.
If you're looking to turn the CC on an app like Prime, hit the up arrow twice. It will show a Subtitle button. Turn it on.
For CC on cable, use the Accessibility on the home button (found in settings). This alone does not work on the apps. You need to do the arrow set up on the apps for some reason.
This is what worked for me.