Display apparatus, control method thereof, and display system

A display device of a display system which comprises a plurality of display devices according to an embodiment of the present invention includes: a display unit; a signal processing unit for processing an image signal based on configuration information pre-stored in a display device to display an image signal from the outside on the display unit; a connection unit which an external storage device having configuration information of the display device is capable of connecting to; and a control unit for storing the configuration information from the external storage device when the external storage device is connected to the connection unit when initially configuring the configuration information for the display device and updating the configuration information stored in the external storage device to correspond to other display device among the plurality of display devices. [Reference numerals] (AA) Start; (BB) End; (S100) Connecting to an external storage device; (S110) Acquiring configuration information from the external storage device; (S120) Storing the acquired configuration information; (S130) Updating the configuration information stored in the external storage device to correspond to a second display device; (S140) Image signal received?; (S150) Access the stored configuration information; (S160) Displaying the image signal as a video based on the configuration information