I found, after grading an assignment, that it was more difficult than I intended, so I'd like to reduce the weight of the assignment. I gave letter grades for the assignment, so I should be able to change the weight freely, right?
Wrong! If I reduce the weight of the assignment, it changes all the grades to A, because it doesn't actually remember what I entered, only some bogus number of points that it assigned, and if I change the weight of the assignment, it thinks everyone did great!
So how do I change the weight of an assignment after grading it? I don't want to move it out of the assignment group it is in, because that would screw up the weighting of the different groups. (I've got already got four different groups of assignments, each with 5–12 assignments in it.)