Without a license Preview Only is enabled and cannot be modified. Once you have installed a license Preview Only remains enabled but now you can disable it.
By default Fix Songs runs with Preview Only enabled. This allows you to see what SongKong would change without modifying your music files.
After Fix Songs completes, review the report. If you are happy with the results, use Apply Preview to apply those changes to your files.
Alternatively, experienced users who are confident with their settings can disable Preview Only before starting Fix Songs, in which case changes are made as the task runs.
