Creating backups is enabled by default. You can turn on/off backups creation option in the Application Menu -> Options.
To back up your interaction, switch on the 'Automatically create interaction backups' option.
If the option is enabled, a backup file of the previous version is created each time when you save an interaction. Each new backup copy replaces the previous backup copy. Visuals saves the backup file in the same folder as the original interaction. The name of the backup file adds the word 'backup' to the file name, for example: Book and Book (backup).