The image forming device determines, on the basis of inputted authentication information and current authentication information, whether to permit use of the web server. In a case that the use of the web server has been permitted and the current authentication information has not matched an initial authentication information, the image forming device transmits, as a web server, data for displaying a web page. In a case that the use of the web server has been permitted and the current authentication information has matched the initial authentication information, the image forming device transmits data for displaying an authentication changing web page. The authentication changing web page is for receiving new authentication information to issue a second instruction. In response to receiving the second instruction, the device updates the current authentication information in the memory using the new authentication information according to the second instruction.