The Default Assignee is a team member that gets all new tasks assigned to him/her by default.
Every TrackDuck project can have a different Default Assignee.
You can set the Default Assignee in TrackDuck Project Settings>Setup.
Choose a person from the dropdown list to make that person a default assignee. All tasks created in this project will be assigned to this person by default. Also all feedback created via Visitors Feedback will be assigned to this person automatically.