come on you must know how to use window$?

my best guess is you plugged the cable and windoze has installed the driver?

go to windows / properties
click on hardware (usb cable must be plugged)
you see in the comport section the cable driver
change that driver and you point it to the jetcat driver *.inf
after this dont let it restart , click on the properties again
go to advanced
change the comport to com 2/3/4/5
after this it should work fine
the jetcat software finds his own comport

OR

plug the cable
go to properties / look for the cable in the comport section
uninstall / unplug the cable
plug the cable / it wants to look for the driver in windoze/update
dont let it instead point it to the place where the jetcat drivers are.
still check the comport if its not to high(>5)