Here you go:

SD.IncidentManagement

=> Main Incident Work

=> Customer Confirm Resolution

=> Survey Task (Dialog Workflow)

=>Scroll down to Task Assignments +. Person Assignments (elispse)

=> Remove "SubmittingContact.ReferenceName

=> Click "Add"

=> Click "From Process"

=> Click "Pick Single"

=> Expand "AffectedUser"

=> Select "ReferenceName"

=> Click OK in till you are back at SD.IncidentManagement

=> Save/Publish 

Any you should be golden. Let me know if it doesn't work. 

After thinking about this I may have been looking at the wrong server (7.1) - if this doesn't work let me know and I will go over it again. 

sd7.1 sp1 you change the survey percentage in the following location - it does not tell you this in the SD 7.1  user guide. 

Home > Admin > Data > Lists and Profiles > View All Items>General Setings> SurveyPercentage