WetGeek I changed some other options, but didn't notice that one.
I think I didn't notice it because it was in the General category, and I didn't look there. I just looked in the OS category. I searched more diligently this time, starting at the beginning, and found it in General.
I was able to correct some things that were not quite right the first time, and indeed created a viable UEFI VM from the Solus 4.3 Budgie ISO file. All my configuration worked without a problem, until I got to the point where I wanted to mount my NAS shares. (A familiar stopping point.)
Although I'd done all the preparation, including modifying /etc/fstab and creating the correct mounting points in /mnt, when I gave the mount -a command, I got a list of errors telling me that the NAS server couldn't be found.
I had been able to browse to that NAS using Vivaldi, and log on, so I know the network connection was correct, and it was accessing my home network. But Nautilus was likewise unable to find the NAS. I fail to understand how I can browse to the NAS server and log onto it, but neither the mount command nor the file manager can access it.
I've bee working on this for the better part of two days now, and I need to take a break for a while, maybe a day or two. I've been putting off things I need to get done. I'll fuss with this again later. Once again, thanks for all the help.