If I may offer a couple of suggestions. As one person above mentioned, there is massive hindrance when implementing new software without proper support or fully functional replacement software. For example, Microsoft Word 2019 is the latest iteration of Word, yet no one skipped a beat with document creation when 2019 came out, because it included mostly all of Word's feature and then some. However, with OneNote, there was this 'app' that was like a go between with OneNote 2016, and with my experience, I installed Office 365, and without warning or support, my OneNote 2016 icon has disappeared. Now, I am forced to waste time trying to figure out to get my notebooks with absolutely critical information stored in them. My suggestion is that when implementing new versions of software, program some type of notice into the install so that users are aware of drastic changes to group software structure, like Office 365.
Second suggestion is creating libraries to help better organize notebooks from a visual stand point. For example, I have 3 major categories of notebooks stored locally and in the cloud, which are access on my desktop machine and my laptop. Those categories are personal notebooks, school notebooks, and work notebooks. I also have projects which may span between all three notebooks. A library would help visually organize my notebooks to quickly access content that is relevant to my current user experience. For example, I have approximately 10 different notebooks pertaining to work, 15 personal notebooks, and 7 school notebooks; however, there is a project that I am working on for personal fulfillment that I am also incorporating into a project at work, which is also being used for a school project. My library would look like this: 1. Personal Library with all 15 notebooks 2. School Library with all 7 school notebooks 3. 10 work notebooks and 4. Project Library with 1 or more notebooks.
One might believe that I am not using OneNote efficiently; however, as a person with over 30 notebooks, it's easy to get books confused and make it difficult to find the right notebook in hurry, or basically keeping my information organized in a logical fashion. I am one of those people who use like 3 iterations of notebooks at the same time, because I am always cross referencing information. Perhaps there are thousands of others who may benefit from having a library feature as well.