To edit a Survey's participants and their answers, follow these steps:
Click on the "Surveys" tab located at the top of the administrative user interface.
Select the Survey for which you want to edit the participants responses in the list of Surveys below the "Surveys" small tab located on the left hand side of the administrative user interface.
Click on the "Manage" button. A window will open displaying the all the Survey's participants in a grid. The grid displays 20 participants per page. You will find controls to view the grid's other pages at the bottom of the grid.
In the grid select the participant for which you want to modify answers.
Click on the arrow on the right of the "Edit" button.
Click on the "Complete" button to edit the responses in the "Complete" mode, or click on the "Fields" button to edit the responses in the "Fields" mode.
Make the desired changes and press the "Save" button.