I downloaded and modified a style file and placed it in the Notepad++ themes folder. I was able to select it and have it update the style as expected. I then went to Setti
The reason is that Notepad++ install all the files at administrator profile, if you are using another user then you are screw, it will not work properly, you have to run it always as an administrator so it can work properly. To avoid this, just do as i said.