Choose Wireless > Access Points > Global Configuration to open the Global Configuration page.
Under 802.1x Supplicant Credentials, select the 802.1x Authentication check box. In the Username text box, enter the username that is to be inherited by all access points that join the controller.
https://www.cisco.com/c/en/us/td/docs/wireless/controller/7-6/configuration- guide/b_cg76/b_cg76_chapter_01101000.pdf