Change all file type associations from one program to another

Solution 1:

In many programs you can set file types associated with the program itself from settings. For example in Notepad++ you can go to Settings -> Preferences and select tab File Association. There you can add files that should be associated with notepad++.

This is not direct answer to what you asked but it should accomplish the same task. In case the program you want to set associations with doesn't have this option you will have to use your method.

Solution 2:

T. Kaltnekar's answer is fine for this program, but Default Programs Editor can do this for any program and any context menu action for any number of extensions.

Open the program, click File Type Settings. The search box, in addition to searching extensions and descriptions, supports limited advanced queries, in the format <verb>:<application>, where "verb" means the item on the file type's context menu, and "application" is the program that item launches when clicked.

So in your case, you'd search for open:notepad to get a list of all file types that Open with Notepad:

You can then select all the items you want out of that list (Ctrl+Click, Shift+Click or Click+Drag like normal) then hit Next.

On the Context Menu page, click the item you want to edit (Open in this case) and click Edit Selected Command. Then you're on this page, where you put in the path to the program of your choice. For you, this is Notepad++ (%1 is the parameter you pass the program so that it opens the file you've clicked. It's a common Windows thing):

Then Next, Save Context Menu, and you're done.

Solution 3:

There is also a quite handy software called FiletypesMan that's very convenient to have around when dealing with filetypes.