psychedelic subtitle background

I've ripped my movie collection to mkv files and whenever a film has subtitles, I've only included the English track so as to avoid a need to choose a subtitle track. I'm using the Transparency skin.

Prior to using mkv files, all my DVDs were ripped as ISOs (I changed because some of the DVD menus were behaving unpredictably so I decided to eliminate menus all together). In the instances where there were subtitles, these would appear in a 28pt font as white text with the movie as background. With the mkv equivalents the subtitles are a black font with a bright yellow background (the translation itself seems fine). I haven't changed any settings so am wondering what to do. Plain white fonts are just a little less distracting!

P.S. (i) changing the subtitle settings in Settings --> Video --> Subtitles has no effect in the current colour scheme; and (ii) if I try and play one of the mkv files using VLC, the subtitles appear in white like they used to.

Guisettings.xml has

<subtitles>
<align>0</align>
<charset>DEFAULT</charset>
<color>1</color>
<custompath pathversion="1"></custompath>
<font>arial.ttf</font>
<height>28</height>
<overrideassfonts>false</overrideassfonts>
<style>1</style>
</subtitles>

See if this is the same for yours. There's a lot more in the file script-XBMC-Subtitles-main located in the skin folder.. Ronie (Skinner of Transparency!) would be the best to know what to look for, but you could experiment changing colour designations... and see what changes might be.

Thanks for the reply PatK. I'll do some experimenting and see what happens. At least I've got somewhere to look now!