If it says you are not authorized when you are trying to update to "Mac OS Update Combined," please follow the instructions below to fix the problem.
Navigate to "Updates" Folder
- In Finder, click on "Mac OS X" in the left panel.
- Open the "Library" folder.
- Open the "Updates" folder.
- Select everything in that folder.
Move Items in the "Updates" Folder to Trash
- Right-click selected items to reveal a drop-down menu.
- From the drop-down menu, select "Move to Trash."