Option to connect USB to the Mac or Virtual Machine has disappeared & no image available

Hi.
I am very new to Parallels. I only bought it yesterday and I'm regretting it already.
I am trying to install Windows 10 to the virtual machine.
When I originally installed Parallels, I was given the option of connecting a USB device to the Mac or the Virtual Machine.
The window with this option no longer appears and the USB always selects to the Mac.
When I am trying to install windows from an ISO file (as per the instructions on the support pages) it will only find the ISO file on the USB stick if the Mac is showing the drive. Then when installing it says it "No images available".
I have tried following the instructions on the support pages, but that just says to select the USB to the virtual machine via the window that no longer comes up!
I'm pulling my hair out now as nothing seems particularly relevant to my setup on the help pages.
I am running OS Sierra, which doesn't allow me to make the USB bootable.
Please help.

 

Hello @AdrianH4. If installing Windows is all you need right now, then please follow the steps below:
------------------------------------------------------------------------------------------------------
1. Download a Windows disk image file and ensure that the download completes successfully.
2. Proceed to install Windows, using the disk image file downloaded earlier.
3. When you come upon the option 'Express Installation', disable it and click on 'Continue'.
4. In the screen saying "Name and Location" on the top, select 'Customize settings before installation' and click on 'Continue'.
5. In the virtual machine configuration window that appears, navigate to Hardware -> CPU & Memory and allocate 2 processors (or just 1 if the total number of available processors is just 2) and 2 GB of memory for Windows [or just 1 GB if total Mac memory is only 2 GB (or) 3 GB if total Mac memory is 8 GB (or) 4 GB if total Mac memory is > 8 GB]. Then, select 'Graphics' and allocate atleast 512 MB of video memory for Windows. Close the window and proceed with the installation.
6. After Windows installation completes, please install Parallels Tools.
------------------------------------------------------------------------------------------------------

 

Hi.
I have followed that method. It now tells me that the Windows 10 Key is not valid. It was working previously.

 

Please refer to our instructions in the support ticket that you've created with us.