• There is no save button on OneNote Online: the application automatically saves the changes to your OneDrive as you type, ensuring you have the most up-to-date version of your notebook and means you don't need to manually save your notebook yourself.
• This icon shows the last time the workbook was ‘synced’ and saved to Onedrive:

Please Note: This is only for OneNote Online. You will need to manually save your work on OneNote Desktop. If you wish to automatically save your work to OneDrive from OneNote Desktop, you will need to turn on this feature. Instructions on how to do this can be found here.