This used to be simple to do, a few releases of Windows ago, but now that windows has been improved, it’s not so simple. You can fairly easily change the default action for “open”, but edit?? Not so simple. Perusal of net.wisdom on the subject usually yields registry hacks and the like. Big fail for Microsoft for removing this ability.
However, all is not lost! Enter Default Programs Editor – yay! This little program is really great. It does a lot and is easy to use. It’s your one stop shop for customizing things the way you want them to work. I downloaded it, ran it, changed the edit functionality I wanted for a specific file type, and then tossed off a donation to the author because it’s so nice to see a simple solution with no adware or other junk, and a decent user interface.
Give it a try!