The ribbon is the band-like command interface that spans the top of the OneNote app window.
Clicking a ribbon tab reveals the commands available in that category. Some ribbon tabs are hidden until they are needed. Clicking any command on the ribbon applies that command to a selection you’ve made in OneNote.
To maximize your screen space for note-taking, you can hide the ribbon so only its tabs are shown. In the upper right-hand corner of the OneNote app window, do either of the following:
To hide the ribbon, click the upward-facing arrow.
To show the ribbon again, click the downward-facing arrow.
Keeping the ribbon expanded at all times is a good idea if you’re still new to OneNote and you want to discover its capabilities more easily. You can easily keep it hidden once you become more proficient with the OneNote interface and its available keyboard shortcuts.
Note: Some functionality in OneNote 2016 for Mac is contextual — controlled by direct interaction with certain interface or page elements. You can often reveal quick access to time-saving sub-commands by Control-clicking such elements in your notes, or by exploring the commands on the OneNote menu bar on your Mac. Either way, be sure to browse through all parts of the OneNote interface to learn and take full advantage of the app’s less obvious capabilities.