Hey Doc; try this, open OD2 config, Style/Color, Change Background, select background you wish to edit, right click select Open skin's settings file, make changes.
When I edit a .ini I never select save from File menu, I just close notepad and then click yes on dialog about saving changes.
After changes saved select another skin, let in apply, which it will automatically do just by selecting it in list, then select the skin you have just edited to see changes.