It works OK now, but I think you need to add a Help button to tell people what it does and how to set up a VM
VM Starter is a ....
How to set up your VM in VBox
IDE controllers have 4 ports, for SATA controllers you can set the Port Count in the VM.
USB 1 and USB 2 will be added to the first available ports on the first disk controller it finds in the VM.
Therefore ensure that you have a free port and that your Port Count is high enough to include your USB drives.
If you want the VM to boot from the USB drive, leave the first port on the first controller free for VMS to add the USB drive:
e.g. leave Primary Master IDE port free if first controller is an IDE HDD,
leave SATA Port 0 free if first controller is a SATA Controller.
or maybe a ReadMe or PDF with pictures would help?