A computer program product includes a non-transitory computer-usable medium having computer-readable program codes embodied in the medium. The program codes when executed cause a computer to execute: detecting a connection status of an externally connected second display different from a built-in first display; writing status information indicating the detected connection status in a storage, changing over a display destination between the first display and the second display based on the detected connection status, and controlling a display screen according to screen specifications of the first display or the second display, which corresponds to the display destination after changeover; and reading the connection status written in the storage and scaling a display image at a magnification based on the read connection status.