The Snapshots panel lets you 'save' multiple states of your document in the same file, and restore your document to any of these states in an instant.
In the Photo Persona, the Snapshots panel can be switched on via View>Studio.
Snapshots are created manually at any time you choose.
By default, a snapshot's name is its date and time of creation, but you can provide a name that is more meaningful to you.
Restoring a snapshot does not delete it or any other snapshot from your document. When a snapshot is no longer required, you must manually delete it.
In the Photo Persona, the following options are available on the panel: