Phonak Audeo Lumity Life L90: Any way to make microphones default to "Off"?

On my phone (Samsung) it is on the call screen, same screen that has “Speakerphone” button. I think my bluetooth button is the top right and speakerphone is bottom left, but i could have the location completely wrong.

Did it and that seems to be the answer, although it somehow gets overridden periodically - but it’s no big deal to just reach up and long-press the button again.