There is now a new way to edit the quantity in stock for your Attribute Intersection Quantities. Previously the only way to change the quantity in stock was via an import, you can now edit these quantities via an Edit screen. To access this feature visit Inventory–>Items–>Attribute Intersection–>View/Edit.
Adding new intersection quantities can still only be done via the import utility.
Only the quantity is editable from the screen.
Importing is still available for doing mass changes but the edit is a good solution for making only a few changes.