After creating gradebook categories, you are unable to lock down the main category, and can only lock children categories by going up the chain, and this locking does not cascade down from any parent categories.

1. Create 2 gradebook categories (Assignments & Exams) under the main course category with another category within the first category created (Lets call it 'Overdue assignments'),
2. Edit the settings for the main category and click the checkbox 'Locked' then click save,
   NOTE: Main category total is not locked
3. Edit the settings for the next category (A) and click the checkbox 'locked' then click save,
   NOTE: category is not locked
4. Edit the settings for category 'C' within category 'A' and click the checkbox 'locked' then click save,
   Note: This has locked the category.
5. Edit the settings for category 'A' and click the checkbox 'locked' then click save,
   NOTE: This has not saved,
6. Repeat the previous action,
   NOTE: The category total is now locked.
7. Edit the settings for the main category and click the checkbox 'locked' then save,
   NOTE: This is still not saving the locked setting on the main category, and this does not cascade down through the children categories.