This setting permits to select how the content of the module will be displayed. In order to set it, when logged in as an administrator, you have to mouse over the arrow beside the title of the module.

Select Settings. Or click the icon  at the bottom of each module. Click Page Settings.

At Visibility there will be 3 options Minimized, Maximized, None.
By selecting Minimize only the module title, header and footer are displayed. The content can be displayed by clicking the maximized (+) button:

By selecting Maximized the whole content of the module will be viewed, with the possibility to reduce the module by clicking the minimized (-) button:

By selecting None the whole module will be displayed, without the possibility to reduce it:

Click Update.