Hi, Martinez,
Thank you for your time. I tried your method, and sadly it didn't work. I then messed around disabling, uninstalling, reinstalling microphones, headphones and speakers, and none of that work either. Until yesterday when, by chance, I discovered that I could switch speakers to headphones just as advertised. Alleluia, I thought, but… Today it doesn't work again. There are times when I absolutely hate computers! I will keep trying of course because when it does what I want it to do, it's a great joy and helps my workflow enormously. But for the moment I have to do some of that work and stop messing about with a hardware. Once again, thank you for your time and your advice. With all good wishes.