Change the function of the red X in the upper right corner to "exit and sign out." This would shift the burden of understanding logout options to power users rather than regular users, who are accustomed to the red X being the method to completely close most applications. It is a constant struggle in my organization to get users completely out of the system in the evenings and on weekends. They leave records open and hit the red X, thinking that everything closes and that they are completely out of the system.