...
You can also use this page to offer extra credit! Marking a question active/extra credit means that the points listed will not be summed in the assignment's total points, but will be granted if students get it correct. If you want students to be able to miss one question and still get a perfect score you can mark any one question extra credit, and because the assignment points will total, this will functionally reach the goal.
Another possibility on this page is to change the number of points a question is worth. Just change the points and click save.
Additionally, on the homework page you can provide feedback about the problem with the question by hitting the little yellow flag icon on the right. That will take you to a page where you can indicate how we can fix the question for future usage: Reporting an error in a question.
...