My amp is not connected to any PC, never has been, so that's not an issue. I did the 5 second hold on the "A" button, but it goes right into the "reset" message, So I don't know if that helped.
The more I use the process of illimination, it appears that I can set my first preset on any of the four letters, but then when I try to set a second one, it wipes out the first one. So basically it's only holding one preset at a time.