@1191658422 , per How do I view grading periods in a course? , grades in a closed grading period cannot be edited. This is by design, as editing assignments or changing grades on those assignments would damage the integrity of the grades for that grading period. Your best course of action would be to reach out to the local Canvas admin for your district who manages grading period dates to find out whether or how they will permit changes to activities in a closed grading period.
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