The new Windows GUI for associating cert file extensions (.nfo, .7z, etc.) is a horrible, awful, useless mess of utter garbage.
assoc command. This can only be run from Command Prompt, it does not work
in PowerShell. Must run as admin.
If you type just
assoc, you will get a list of all extensions with an associated
program and what that associated program is.
To set a new association, you do something like this: