This feature is available in Catalyst, Enterprise, and Ultimate editions.
List Values are the options that display in drop-down menus throughout the system. Follow the instructions in this article to edit any of the list value details.
List Type Administration functions are only available to users with an Admin Privileges role of "System Administrator".
From the Admin menu, select List Types.
Select a List Type tab (Task, Test, Story/Backlog Item, etc.), and then navigate to the desired List Name section.
Change the information as appropriate, and then click Save.
You can add list type values to Global assets very easily as well. See below for an example.
Q: Is it possible to add a type to attachments? I see on our attachments(inside backlog items) an option to add a type, however, is blank, where would I add as an admin these attachment types?
A: You can add Type values for Attachments by going to Administration > List Types > Global. Locate the Attachment Type, and add the values you would like to appear in the dropdown.