Your account username appears in the URLs of your surveys:
To change your account username and update your survey URLs, please fill out our support request form and include the email address listed on your account and the username you’d like to update to. A friendly support representative will be happy to make this change for you.
Changing your username affects all surveys in your account, including older surveys. You will need to update all Deploy links and Embed collectors for these links to remain live.
NOTE: Changing your nickname in your user preferences does not update the username in your URLs.