[Calyr Elf]

Hello, I'm new and I apologize if I'm not familiar with everything yet, but I'm hoping someone will tolerate a newbie question.

After I installed Sigil, suddenly, it became my default text editor and all of my text files had the Sigil icon. I don't want this; I want Notepad plus plus to be my default text editor. The only thing I seem to be able to do is load my text files in Sigil, and then copy and paste them into Notepad plus plus. That's so annoying. How can I change that without uninstalling Sigil? I love Sigil in many ways, but I feel like it has taken over my entire computer. What did I do wrong?

Any help is appreciated. Calyr