How to change school grade on blackboard

The roles of instructor, teaching assistant, and grader can change grades in a course. When you change grades, the new data is automatically figured into existing weighted, total, or calculated grade columns. Each time you change a grade, an entry is made in the grade history.
Sometimes a grade change results in an override grade. A true override grade is applied to attempt-based Grade Center items only-tests and assignments. An override grade takes precedence over all other grade entries, including attempts a student submits after you assign an override grade.

For example, a grade is based on the average of multiple assignment attempts. But, you want to add a grade for a certain student that is one other than the average. For that student, you can assign an override grade that takes precedence over all other grades and future attempts.