sync bin - listen to timeline audio instead of clip audio?

I saw a post sometime in the past year that mentioned how to set the sync bin to play the timeline audio instead of the audio from the primary cut page clip. I set one machine up like this and it's great. But now I have another installation of Resolve and can't figure this out. And I can't seem to find that post either. My googlefu has no kills (so far).

Anyone care to share the secret? I seem to recall that it was very simple (one click) but not intuitive to find.