I have several Bluetooth headsets that have a function button in addition to volume up and volume down buttons.
How can I specify – or even determine – what the effects are of pushing that button?
While such a headset is connected to my iPhone XS, pressing the function button once often toggles pause/play on the current music player app (even if in the background). If I double-click the button ... weirdness. E.g., it might initiate a phone call to the last person I called.