Typically the edit operation is used to modify anything about the task.  However, typically editing a task is used to modify the priority, progress and/or mark the task complete.  Some edit operations may be performed directly from the tasks list.  the operations are:

1.Modifying the progress of of a task

2.Marking a task complete

Other modifications to the task require a full task edit operation.

To Edit a Task,

1.From the To Do List screen, click the action menu and select "Edit Task"

2.Modify the desired fields

3.Click the "Update" button