Slitherine

I've been trying to modify severe winter values in the general text file in the data folder; I can get into the file and change the related numbers, but when I try to close the file I get question about save/replace file. When I answer yes, I get an error message that I do not have permission to open the file, and that I should contact the file owner or an administrator.

I am the administrator, using the administrator UAC.

Can you help me find a way to modify severe winter?