A display apparatus, comprising: a display configured to display a user interface screen; an input unit implemented as a single physical function key and configured to receive a user operation to select one of a plurality of menu items included in the user interface screen and execute a function corresponding to a selected menu item; and a processor configured to: recognize a short click and a long press based on an input time duration of the user operation; constantly maintain an execution speed of a function corresponding to the selected menu item within a preset critical time duration during which the long press is input; accelerate the execution speed of the corresponding function as the long press is input longer than the preset critical time duration; and move a selection GUI, which is implemented as a form enclosing a menu item or by a cursor or by changing a color of a menu item, for selecting one of the plurality of menu items included in the user interface screen when the user operation is recognized as the short click and to select and execute a function corresponding to a menu item at which the selection GUI is positioned when the user operation is recognized as the long press. a display configured to display a user interface screen; an input unit implemented as a single physical function key and configured to receive a user operation to select one of a plurality of menu items included in the user interface screen and execute a function corresponding to a selected menu item; and a processor configured to: recognize a short click and a long press based on an input time duration of the user operation; constantly maintain an execution speed of a function corresponding to the selected menu item within a preset critical time duration during which the long press is input; accelerate the execution speed of the corresponding function as the long press is input longer than the preset critical time duration; and move a selection GUI, which is implemented as a form enclosing a menu item or by a cursor or by changing a color of a menu item, for selecting one of the plurality of menu items included in the user interface screen when the user operation is recognized as the short click and to select and execute a function corresponding to a menu item at which the selection GUI is positioned when the user operation is recognized as the long press. recognize a short click and a long press based on an input time duration of the user operation; constantly maintain an execution speed of a function corresponding to the selected menu item within a preset critical time duration during which the long press is input; accelerate the execution speed of the corresponding function as the long press is input longer than the preset critical time duration; and move a selection GUI, which is implemented as a form enclosing a menu item or by a cursor or by changing a color of a menu item, for selecting one of the plurality of menu items included in the user interface screen when the user operation is recognized as the short click and to select and execute a function corresponding to a menu item at which the selection GUI is positioned when the user operation is recognized as the long press.