You can edit marks for students in a previous class by going to:
Menu > Academics > Examination > Exam Management > Create Exam
- Select a year.
- On the class-wise tab, select the Inactive classes radio button.
- Click Manage exams beside the class you want.
- Click Manage exams beside the exam group.
- Select a subject, and then edit the marks.
- Select the Retake check-box if the student is retaking the exam.
- Click the Save button.