Open Run menu by pressing Windows key + R
Type "netplwiz" (without quotes) and press Enter. This will open the "User Accounts" window.
In the "User Accounts" window, select the user account for which you want to change the username on the lock screen, and then click on the "Properties" button.
In the "User Properties" window, you'll see two text fields: "User name" and "Full name." The "Full name" field is what determines the display name shown on the lock screen.
Change the "Full name" to the desired username you want to see on the lock screen, and then click "OK" to apply the changes.
You may be prompted to enter the account's password for confirmation.
Restart your computer to see the updated username on the lock screen.