when you have the device installed open up device manager, right click on it and select properties, choose the advanced tab then click advanced port settings, shoose the available com port you want and ok all the boxes, you may need to restart the computer for the change to take effect. If the software only lets you choose the first set of com ports and they are all reserved by other devices, like vagcom does, you will have to find what is using the com port you want to assign by doing the above on other connected devices like modems etc and re assign them a com port out of the range you want