

The way I do such things is directly in the Windows Registry using regedit.exe (please note that editing the registry does have dangers as well, but that if you follow directions, you generally won’t mess anything up).

Because the question “how do I change the icons of all text files” is the same as “how do I change the icons for all image files” or “how do I change the icons for all PDF files” – you use Windows tools to do so. As an alternative to editing the icon inside the executable (which has the dangers that you could easily corrupt the executable into not working right, and means that you would have to edit the icon every time you updated Notepad++ to a newer version which would get annoying), you can use the standard Windows tools for assigning icons.
