Each time you start OneNote for Mac, it reopens the page you last looked at in the notebook you last worked in. Opening additional notebooks adds them to a list of recent notebooks, making it easier to switch between them.
Open a notebook
On the File menu, click Open Notebook (or press Command-O on your keyboard).
If you’re not already signed into your OneDrive account (or an account that was shared with you), click Sign In and then enter your account information when prompted.
In the list of notebooks, click the notebook you want to open, and then click Open.
Note: Depending on your connection speed and the size of the notebook you’re opening, it may take a few moments to load all of its sections and pages. The section tabs may appear grey during this time. Once a section tab changes to its proper color, that particular section has been fully loaded and is ready to use.
Switch to a recently used notebook
If you want to switch to a notebook that you previously opened, click the Show Notebooks button .
In the list of notebooks that opens, click the name of the notebook that you want to switch to. If no other notebooks are shown, click More Notebooks.
Note: Switching to another notebook keeps your previous notebook open. Although not necessary, you can close a notebook if you won’t be working in it anymore. Closing a notebook does not delete its contents — it merely removes its name from your notebooks list.