Why is iMessage the default for my texting now? It used to be green bubble SMS. Now, I hit "send" and go back much later to find "Undelivered". Can I switch back and forth? Looked in Settings but didn't see directions about switching message mode.
Why is iMessage suddenly default for texting from my iPhone 6Plus? I used to use SMS. With iMessage when I "send" it's almost always "Not Delivered" and I must take two step of choosing Text; shouldn't Text be default?
MacBook Air, macOS High Sierra (10.13.2)