You can change the display name of your WordPress account which show on a WordPress post or comments without changing your wordpress username.
1. Login to your WordPress admin dashboard.
2. Under the dashboard menu, hover your mouse over "Users" and then click on "Your Profile".
3. Locate â€œNicknameâ€ and enter your new name.
4. In the option â€œDisplay name publicly asâ€, choose your newly added nickname from the drop-down menu.