To change username go to top right and click on downward arrow on DP
Then go to setting and login and there is username change option box under current username box
However once change username then change username box will not be visible for one year and one can check when username change completing 1 year - go to profile and click on change log option and click on my username and it will tell time of username changing
Username name option are available to only to those
1 who has invalid username ( guidelines of valid username is given when clicking username change option
2 who has never change their username
3 when username change complete 1 year ( like if anyone change username today then for I year username change will be not be visible)
In order to change your Username, first, make sure you have completed 1 year since last time you changed it.
1- Click on your Profile Picture/Dashboard and click on the red Settings button
2-Sign in with your UN and password
3- Now, Under the 'Profile', You'll see your Username above the 'Change Username' (If you completed 1 year or more)
Make sure to follow the Username Policy listed down
Click on Save and you are done!