Preferences dialog
Preferences dialog allows you to set various program options. Some of then can be overridden on note's Adjust dialog, while others remain common for program in whole.
This dialog consists of several tabs:

Tab Description
Appearance Everything related to note's window appearance
Skins Everything related to common notes's skins or skinless notes options
Schedule Everything related to scheduling (date formats, sounds etc)
Docking Everything related to notes's docking
Behavior Everything related to program's behavior
Misc All other options

"Default preferences" button will restore default program preferences.
No changes are applied until you click "OK" or "Apply" button.