As they say in Plan 9 From Outer Space "Stupid, stupid, stupid!" I'm a bit slower these days, I'm 79. Sorry, guys.
Out of the recesses of my mind I remembered Ctrl-Alt-Delete. I did that.
It came...

This is what I used to create Administrator:
At: Attention Required! | Cloudflare
net user administrator /active:yes

Using Windows 10 Pro, Version 21H2.
I was getting these messages about not being the administrator. Of course I was, but couldn't even change a .txt file.
I went on line to find out why, and found...

The problem was that I didn't register my phone.
OK now.

I am running Visual Studio 2015 on Windows 10.
I wrote a simple Windows Phone 8.1 project (Hello World) in Visual Basic.
The program worked all right in the Emulator.
I attached my phone (Lumia...