Need nano 6th gen to stop at the end of a track

I listen to audiobooks that I download from Overdrive. Most of them are MP3 files and automatically download to music in Itunes and I transfer them to my Ipod. My Ipod has always played 1 track and then stopped - which I happen to like. Each track is about an hour in length. Now it is continuing to play on and on. What happened and how do I get it to go back to the way it was? Yes, I know most people have the opposite problem.....