How to change the display name in the Google Play Store app? In the Google Play Store app, the account name is shown inside the drawer menu.

How to change that name?
There should be a pre-installed Android app in your phone called Play Games. Click that. You will see your username and your display pic. Click your username and then the top right edit icon of a pen. That way you can change your Google PlayStore username. 
Hope this helps :)