Assignments appear in the Writer's Help Gradebook in the order in which you create them. If you'd like to change the order--to arrange them by due date, for example--take the following steps.
From the Assignment unit
Click on the arrow to expand the assignment unit that contains the assignment you wish to modify.
Click and drag the assignment. You will see a yellow bar while doing this. Drag and drop the yellow bar (your assignment) where you would like it to be.
Your assignment order has now changed.