Any previously created Attribute Sets associated with your user account are displayed in a list, and are disabled by default.
Specific Attribute Sets can be located using the search box.
To enable the set, toggle the Enable button. This can be clicked again to Disable the set.
Any enabled Sets are counted and displayed in a dynamic list for convenience, which can be disabled in bulk via 'Clear All' - this is especially useful when working with multiple AttrSets simultaneously.