When you select the 'Edit Preferences...' menu command from the 'File' menu on the main window, you will be presented with a dialog box with two panels. The panel on the left presents a hierarchical view of the various settings you can edit. The panel on the right will display the editor for a specific preference when that preference is selected in the tree on the left.
When you edit preferences, your modifications are not committed until you select the "Save" button at the bottom right of the dialog box. If you select the "Cancel" button all of your modifications will be lost and the previous preferences will be left untouched.