What worked for me.
If nothing works, such as q-tip trick, un-plug in and plug in of the headphone, bluetooth speaker trick, the Setting/General/Accessibility/incoming calls (audio routing for newer software)/set speaker, then headset, turning on shazam, activiate siri...etc. TRY THIS, 1) have someone call you, 2) turn on to speaker mode, 3)turn off the speaker, 4) plug in your headphone, 5) un-plug headphone. This should work!
If nothing works, such as q-tip trick, un-plug in and plug in of the headphone, bluetooth speaker trick, the Setting/General/Accessibility/incoming calls (audio routing for newer software)/set speaker, then headset, turning on shazam, activiate siri...etc. TRY THIS, 1) have someone call you, 2) turn on to speaker mode, 3)turn off the speaker, 4) plug in your headphone, 5) un-plug headphone. This should work!