1. An input/output device for selecting an item displayed on screen through a sequence of operations and then executing a function corresponding to the selected item, comprising: input means, to be operated by a user, for inputting user operations; storage means for storing an input operation history of user operations input to the input means; display position adjusting means for adjusting screen display positions of items based on the input operation history stored in the storage means; output means for outputting the items to the screen display positions adjusted by the display position adjusting means; and user learning evaluation means for determining if the user has learned the selection sequence for items selected by the user based on the input operation history stored in the storage means; wherein the display position adjusting means prohibits changing the screen display position of items that the user learning evaluation means determines the user has learned, and adjusts the display position of items that the user learning evaluation means determines the user has not learned; and wherein the user learning evaluation means detects from the input operation history stored in the storage means the type of buttons used to execute a function, determines that the user has learned any item for which the detected buttons include a numeric button, and determines that the user has not learned any item for which the detected buttons include the enter button.