...
The single view in Course Site Gradebook allows for you to filter by assignment or student or groups, as well as clear overrides.
Overrides
You can override a grade by typing in the grader report. This means that the grade will not be auto-calculated in a quiz or synched from another method. You may want to clear this override in the SINGLE VIEW by unchecking and saving your changes.
Don't forget to SAVE save your changes.