Oh, jeez. You're right, of course. I'd made an icon on the Quick Launch menu, but it opens MS Paint instead of Paint.net. No idea why, but I'll delete that icon.
Thanks!
When I first installed Paint.net, all the menus and icons were there, but when I next opened it, they are missing. (I've tried installing twice.) Is it me or the program?
Working in Windows 10. (I had to create the attached image in PhotoShop.)