Problem:
After plugging in the headphones, the computer cannot automatically switch to the headphone output.
Cause:
The speaker is set as the default by mistake, so the default playback device is the speaker after plugging in the headphones.
Solution:
After inserting the headphones, click the small speaker in the lower right corner, select the sounds - choose Playback, select the headphones, click the "Set default" button in the lower right corner, and click OK.