@Kal to turn off closed captioning press OK on the remote and you'll see a CC icon at the bottom of your screen. If the CC icon is green, closed captioning is on, if you click OK again it'll turn white and turn off. Hope that helps.
@t80 if you see it again can you let me know what channel and show you're seeing this on? There should be an AD icon at the bottom you can deselect. Also, this happened on the media box or the phone app?