NET10 was zero help. Finally got through to a chat guy, and he /she was useless.
However, I did find a step by step description of how to change APNs, and it turns out all I needed to do was press the Menu key at the right window, and I could access the APNs! Eventually found settings that worked when used.
I am now running on 4G! Thanks all for trying to help the incompetent.
Or, as Roseanna Roseannadanna would say, “Never mind.”
I’m glad that it worked!