An operation device of an image forming apparatus, a display method, and an image forming apparatus. A display unit displays a basic screen including a setting information display area to display setting information and a button display area in which an icon is displayed as a setting button screen. A touch panel detects a contact position on a display screen of the display unit. A display control unit displays, on the display unit, a selection screen including a plurality of options corresponding to a setting particular of the icon displayed in a position where a contact is detected by the touch panel, displays a result selected in the selection screen as new setting information in the setting information display area in the basic screen, and displays a triangular graphic which associates the icon with the setting information corresponding to the setting particular of the icon.