Why do I see a big black box/words scrolling at the bottom of my screen?

Closed Captioning (CC) is turned on either on your TV or through the converter or TiVo. 

On your converter you will find the option to turn on or off CC under MENU then SET UP.

On your TiVo you will find it under the INFO (i) button

On most TV’s you should find it under SETTINGS or MENU button on your remote that came with your TV.