Trint saves automatically at regular intervals. When you make an edit to the file, the time the file last saved briefly pops up under Version History on the left.
How do I access previous versions of my file?
Once you've opened your file, you will see Version History on the left.
You can select any one of these versions to restore it. This will not erase your current version, it will create a copy of the selected version.
You can choose to rename it and share with the same collaborators.
Please note, version history is not available for Story or Caption files.