If I understand it correctly, in the 'SkinInfo' configuration settings if I want to change the default then all I do is chose one of the themes below the default then copy and paste that after default?
Example:
ThemeEffects_Default=AUTOLEVELS
remove 'AUTOLEVELS' and replace with,
ThemeEffects_Default="Holy Crown - Gold"|REPLACECOLOR:#d8dfef,#FCC200,27|SCALELUMA:300,980