Hi Tricia,
Tried both the latest episodes of these, and subtitles are showing.
When viewing these in Iplayer, and you press the subtitle button on the remote, does it underline the 'S' at the bottom of the Iplayer window. This usually indicates this is on.
If so, and no subtitles are showing, then next option is to try a full YouView Reset of the box.
Thanks
Karl.