The button 1 let you restore all the preferences to their default values, as when you installed BlueBrick for the first time. The button 2 let you restore only the preferences displayed on the current visible category.
The default Color Scheme 3 is "Blue Print" You can also select a Parchment or Classic version. Custom color schemes can be made by choosing your colors by clicking on the color boxes next to the following text entries: "Background Color", "Default Grid Color" and "Default sub-grid Color". Below, you can adjust the highlight percentage for the selected parts and for the single part you grab in a group of selected parts. You can also set the default color and size of the item hull (this apply to parts, texts and rulers). The result of your color settings will be shown in the preview window. The changes will not take effect until after press the "Ok" button.
You can also set the default text format 4 (font style and color) which will be used each time you create a new text on your map. This settings also affect the dimension displayed by the rulers.
Similarly you can set the default settings for each new grid layer 5 and each new area layer 6. To tune the default ruler style see the Edition Preference section.