I would like to change my username to NutritionDynamic.

The username "NutritionDynamic" is available to be used, however, we could not find any username registered under your email address "keoniglory@yahoo.com".

Please login to your JotForm account to open a new forum thread to make the request. Please note that if you are using custom URLs, they will no longer work once the username is changed, so you will have to create new ones: https://www.jotform.com/help/261-How-to-Create-a-Custom-URL-of-a-Form