To access the survey feature, navigate to menu > dashboard > surveys.
Each survey listed on this page will show you the name, which group of users it applies to, and the number of responses the survey has received. You can edit a survey up to the start time of the survey by tapping the down arrow to the right of each event.
From the edit page, you can change any details of the survey, including the questions.
*Note: once the survey starts you can't edit it, you can only stop it.
Learn to export survey results.