The settings window allows you to control album-wide aspects. Each album project maintains a unique set of settings. These album-wide settings (unlike image specific settings) needs to be saved with the album project to be persisted so remember to issue File->Save project when you're happy with your new settings.
The settings window is divided into the following sections:
At the bottom there are two buttons: "Ok" and "Apply". You usually only use "Ok" to confirm the settings and close the window, but when having the preview view mode open, these buttons operate like this: