I'm trying to disconnect the volume control from connected devices, so that hitting the volume buttons on my phone doesn't change the playback volume.
Others mention going to Settings > Devices, and disabling "Devices Lock Screen."
But I see no such option in settings, and under "Devices," I only see a "Open Devices Menu" button, which just opens the pop-up to switch between devices...
iPhone SE / MacBook Pro
(iOS 11.4, OS 10.11.6.)