Every time you edit your manuscript, your edits are saved to the cloud. This save happens every 3 seconds, or after you stop typing. Every 10 saves, we store a snapshot of the scene you are editing.
You can see the last 5 saved snapshots for each scene if you hover over the "Last saved..." text in the bottom toolbar.
Click on one of these snapshots to view the content in that snapshot:
You can copy text out of this snapshot, or choose to revert to this version of your scene. If you do choose to revert, this will overwrite the content in your existing scene with this content, so make sure this is what you want to do.