After you've saved your lesson for the first time. We'll autosave any changes you make every time you switch between pages.
When you save your lesson, this will appear in the toolbar:
You can choose to automatically save your lesson as you work, so each time you move on to a new slide, you’ll receive a message that all changes were saved.
Alternatively, you can turn this feature off and just save manually. This way, any changes like moving covers or making annotations won't be saved to your lesson.