Mystery solved

Yes, I was really confused when a user told me he was not able to modify the config files. After several emails back and forth, I finally found the problem. He is opening the config files directly inside zip files and trying to save them (Thanks to Windows for making it so convenient).

And I think that also explains why so many people asking me about the bot complains "Can't find settings.txt", yep, they must tried to run it in the zip file as well.