Two different situations:
1. user wants to change his username – (advanced)
2. user wants to change how his name appears in email and when he logs into web-site dashboard.
Chances are user wants to change his username.
Wordpress doesn’t allow doing that.
But there is an advanced option allowing changing username.
This video tutorial is private and shared with our team members only as containing security vulnerable information.

2nd Scenario Here:

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