Ratings are a mess. There are virtually no standards as to how ratings are represented or encoded. The ID3 specification allows for multiple ratings, which Yate supports but are rarely used. Typically there is at most one rating which Yate refers to as the default rating.
Settings - Audio allows you to configure various rating mechanisms which can be established for different audio file types. You can even change how the ID3 256 value rating is mapped to five stars. Unfortunately, there are no standards for these mappings either.
If you are moving to a new audio player and it has a different representation system than you are using, you will find that your ratings may appear incorrectly in the player. Further, if you change a rating on the player and it is written to the audio file, the new rating may appear incorrectly in Yate.
Preserved Rating is a mechanism which can be used to handle this changing of rating systems. In the past you could use the Translate Rating action statement to handle the scenario but it is a far more complicated method. The Preserved Rating method, writes an absolute (0-5) value to a UDTI named Preserved Rating whenever saving files. This means that you have a permanent record of a rating value outside of any particular rating scheme. The UDTI is not used when displaying the rating in the UI or when the rating is manipulated in an action. The writing of the UDTI is enabled by the Settings - Audio - Common - Write Preserved Rating option. When enabled, the UDTI is set to the current value of the default rating whenever a file is saved.
A second setting, Settings - Audio - Common - Mark file as modified if Preserved Rating is not equal to the actual rating controls what happens when a file is loaded. When this option is enabled, if you modify a rating in a player and then load the file in Yate, the file will display a red modified indicator. This is to let you know that the file should be saved to update the Preserved Rating UDTI. You can always do a View>Changes to the Initial State to see what has changed.
Note that the current value of the Preserved Rating UDTI is not used by the functionality. Only the initial value is used. However, you should not manually modify the current value as it is used to determine a change when no other changes have been made.
If you want to buy into the preservation system, changing the settings will ensure that future changes are safe. However, what about your existing files? You can run a batch process to preserve your current ratings via Action>Batch Processes>Preserve Current Ratings.
If you change your ratings model you can update your audio files to the new settings by running Action>Batch Processes>Restore Ratings from Preserved Ratings.
The two actions can be run on loaded files without calling the batch processor. When running in the batch processor, warnings will be issued. When running directly on loaded files, warnings are not issued.
The actions will be in the Preloaded Actions folder in the Action Manager. If you have never run the batch processes, you might not have the actions. If this is the case do a Yate>Import Built in Items>Import Actions.