As lots of user uses facebook in mobile , so we will learn first in mobile then further learn in how to change username in desktop ! Unfortunately , When I decided to write blog on this topic I found that I didn’t get any option of editing facebook page or facebook profile from mobile so I think facebook team would have removed this option. So let’s discuss about in desktop version now !
Login to facebook account , and follow the steps carefully and see reference image below for better understanding.
After clicked you see that page, reference image in below ! Highlighted in green rectangular box .