OneNote 2016 for Mac keeps all of your notes in the cloud by automatically syncing them to your OneDrive account automatically. This lets you view and edit your notes anywhere on all of your devices.
There may be times when you want to sync manually, to force syncing a large amount of changes to notes before having to disconnect on short notice (for example, when stepping on an airplane).
Do the following:
Click the Show Notebooks button .
In the notebooks list, Control-click the name of the notebook you want to manually sync, and then click Sync This Notebook.