It is possible to edit your survey until 24 hours before your survey period starts.
Click on the tab “Projects” in the menu on the left in My Effectory to select the project that includes your survey(s), and then click on “View all surveys”. Next, click on the three bullets and the pencil icon to the right of the survey you want to edit.
Within 24 hours before the survey starts you can no longer make any changes. However, it is still possible to delete the survey and create a new one if necessary.