MAC : How to repair Permissions on MAC
If you upgraded your mac with recent update, and some of your apps are behaving weirdly, then you might want to repair the disk permissions.
To perform this launch Disk Utility searching from "Spotlight Search", now from right pane select the disk where mac is installed. on left pane you will see the "Repair Disk Permissions" button. Click this button. This will start the repair operation.
You can also select the "Show Details" check box to see what all permissions are corrected or failed.