The switch beetween headphones and speaker is automatic, music playing works well but when I have a call it switches back to phone speaker.
I have to re-enter this commandline after reboot : pacmd load-module module-udev-detect
@arubislander Thank you. I was trying that several times, and getting rather anxious about it not rebooting, but then finally it did reboot and all is now well again.
But I shan't be trying to use the Wireless Display again very soon ...