I've installed driver to usb device. Windows had created new COM6 port for my device but application used for device need from 1 to 4 port number. So I've opened Device manager, found port USB serial port (COM6) there, selected properties in context menu, clicked tab Port Settings in new form, clicked button Advanced, selected another COM port number, clicked OK but all windows have closed once and port number remained without change (COM6). I don't understand it is Windows OS bug or I do something wrong