Turn on autosave?
Open the “Openbox settings” window and click “Other”. The fourth checkbox from the top allows you to turn on autosave, and set the frequency in minutes.
Note that this will save over the existing file, rather than create a new file for each version.
But if you save your files in a file sharing tool such as Dropbox or OneDrive, they will keep track of versions, allowing you to go back if you need to.