The simplest of modding questions

[zig_zac]

I want to change stats of a unit in EB, not very ambitious project, you may notice. Yet, apparently, it's above my skills.

I started by editing rtw/EB/data/export_descr_unit.txt, didn't help.
The game edited it back upon start. So I marked "read only" option in properties - now the game won't start.
I also edited rtw/data/export_descr_unit.txt, which didn't help either.

What do I do wrong?

I will be grateful for help, as I plan to have great fun with this changes.