I need to clone an existing 6.7 VM with a different OS. I try and customize the Guest OS in the Cloning steps but It doesn't ask me for the location of the ISO file to select. Am I missing something?
A clone is a copy, so if you're cloning a VM that has an OS installed you are creating another VM with that same OS installed.
Customising the OS instance in the new VM is to set parameters such as a host name and IP address.
What are you trying to actually do?