Highlights Going to Wrong Notebook

I just this morning noticed that all my highlights are going to the wrong notebook. I have a notebook named "Thoughts" that I use when making notes in my daily Bible readings. Highlights were supposed to go to "No Notebook".  But for the past 6 months all my highlights (some 1800 of them!) have been going to the "Thoughts" notebook. I am in the process of changing all 1800 to "no notebook", but how I do I set all highlights to go to "No Notebook" in the future? Is there no longer a way to do this? I have no idea what triggered this change in the first place.