I have added a lot of covers to tracks that were missing them but then I discovered that these covers were not saved into the files themselves, they were saved into a cache folder. I have now changed the option to save covers so that they are saved in the files. Is there a way to force the covers that have already been saved into the cache to be re-saved into the files? Else, is there a way to clear this cache so that I can start over? Where is this cache located in a Mac machine?