The first survey question is the NPS standard and cannot be changed.
Under 'settings' you can adjust the product name and the audience you are addressing the survey to. You can further customize the survey by changing the second, open ended follow-up question.
You may additionally customize your survey by adding a third question. We call this the 'social share'. It appears for your promotors and allows them to share how great they feel about your product or service on Twitter or Facebook.
You can learn about how to enable 'social sharing' here.