This page lets you configure a list of music genres that's shown in the dropdown for the Genre field in the metadata pane. A number of genres are pre-defined but you can remove them if you don't need them, and also add your own.
The Unused genres list shows the defined genres that won't be listed, and the Listed genres list shows the ones that will be.
Use the and buttons to move genres between the two lists. You can also double-click a genre to move it to the other list.
You can change the order of the genres in the Listed genres list using the and buttons.
The sort button can be used to resort the genres list alphabetically if the order has been changed.
To add a custom genre, enter it in the field at the bottom of the Unused genres list and click the button.