can't mod "export_descr_unit" file need HELP pls

[Captain Tman]

Hi, first of all I want to say what a great mod this is, I played the original RTW mod too, but this beats all.
Currently I'm playing the Renaissance era and there's only this little problem; I want to change the HP for generals cavalry from 4 to 2 (I think 2 is just about right, but 4 is way overboard especially with an old general with lots of cav). So I went into "mods\SicilianVespers\data", in "export_descr_unit" I changed "stat_health 4, 0" to "stat_health 2, 0", saved, exited and started playing, only to notice that my changes did not take effect in the game, and when I exited I found that in "export_descr_unit" all the things I changed (and saved!) have reverted to the original: "stat_health 2, 0" back to "stat_health 4, 0".
:hmmm:so what's the problem, do I have to mod MTW in a different way, or do I have to unpack some data or what?? I read in a post that there was an "export_descr_unit_renaissance" file somewhere, but I don't seem to have that (I do have dark and early).
btw, I'm playing version 3.2
Hope someone can help, thanks.

[SicilianVespers]

The Early, High, Late & Renaissance campaigns all use the _early EDU.