That setting is actually skin-dependant, so it could be different on each skin.
The way you are setting it up is not the best approach, though for what you may need the alternative may not be that much better..
Options > Preferences > Skins > Modern Skins > Font Rendering > Font > Font Mapper > USE SKIN FONT MAPPER > CONFIGURE SKIN FONT MAPPING.
On the new window, the first options you'll see are skin-specific. Look at the screenshots attached, you'll notice:
1. Winamp modern allows to change independently most fonts (pointed out in red).
2. It isn't really all that good for BIGGER FONTS, the container box chops the fonts when it goes too big.. (this is related to how the skin is done, so there is little to do about it..)
That said, you can test it with other skins, maybe you'll come to something close to what you need, good luck.