STEP 1: Click the Grade Setup link in the NAVIGATION pane.
STEP 2: Click the Letters tab. The current letter grade scale is shown.
STEP 3: Click the Edit button or the Edit grade letters link above the table.
STEP 4: On the Edit grade letters page, make sure you check the box next to Override site defaults. This will enable you to customize the letter grade scale. You can change the letter grades (for example, to add A+), and also the Letter grade boundary.
STEP 5: Change the Letter grades by manually entering a letter grade. Change the Letter grade boundary by entering the correct percentage in the percentage field. To add more letter grades, use the blank, unused entries at the bottom of the page
STEP 6: When you are satisfied with your changes, click the Save Changes button.