Question,...

before you did a "change all" were there three icons for three programs?

if yes,..

I believe there's a prebinding database that stores this info. perhaps removing either the entries for the taco and smultron apps along with deleting the pref files for those apps will bring you back to the beginning. pre "change all" state. It really depends on the app author to give you results that you expect. It seems the text edit app behaves correctly, yet the other two were poorly written.