Plugging in headphones does not switch to headphones.
If I wish to switch from speaker to headphone, the only way is to go into playback devices and select one or the other as default. I can't default both. Checking one as default (speaker) and the other as communication device also doesn't help.
I notice that many others on the forums have a single choice, that is, speaker/headphones. Mine are separate. Also, I have VIA HD Audio(Win 10).
Not sure what other information will help.