You use your display name whenever you sign in to your account. It's also the name you see on your Windows 10 devices, and it's the name people see when you send emails. This name may differ from your local account's display name.
Under your name, select Edit name. If there’s no name listed yet, select Add name.
Enter the name you want, then type the CAPTCHA and select Save. Some names may not be allowed if they contain blocked words or phrases. If you get an error when you enter your name, try a nickname instead.