When Teachers go to their Gradebook Options why are they unable to edit the options?

In Portal Options under the Gradebook tab there is a Lock Options area. If any of the options are selected, the Teacher Gradebook Options page will lock those specific options as enabled. 

The locked Gradebook Options will display in the Teacher Gradebook Options area with a more prominent black border and with a bolder black checkmark as shown below. They will not be edited by the teacher due to the lock.