Here’s a little bit of knowledge I stumbled across. I’ve been trying to set up closed captioning on my Comcast box for a while now, and basically gave up, until I did some searching today and came up with the solution.
On your Comcast remote, press “Cable”, then press “Power”, and within about 2-3 seconds press “Menu”. This will bring up a list of user settings. Closed captioning is at the bottom of the screen.
Then simply hit power again and turn the box back on/off.