You can update existing associations, such as the Default association, which is created automatically when you create a new issue type screen scheme:

1. Browse to the Configure Issue Type Screen Scheme page for the issue type screen scheme to be configured
2. Click on the Edit link for the association you wish to edit. This will take you to the Edit Issue Type Screen Scheme page
3. Select a new screen scheme to associate it with the issue type
4. Click on the Update button to apply the change

You can also delete existing associations for issue types if you no longer need them to be explicitly set. However, you cannot delete the Default association, since it is used as a catch for all of the issue types that do not have an association defined. This is important because, while you may have created associations for all of the issue types right now, you might add new issue types down the line and forget to create associations for them. To delete an association, perform the following steps:

1. Browse to the Configure Issue Type Screen Scheme page for the issue type screen scheme to be configured
2. Click on the Delete link for the association you wish to delete

Just like associations in screen schemes, you will not be taken to a confirmation dialog, and the association will be deleted immediately.