Jtdylktuy

Superusers,

I updated to Windows 10, all nice and well, except one thing: I cannot assign a new program to a file type.
Here are the options:

1. Edit on opening


2. Edit in the properties


3. Edit in Configuration >> Default programs


4. Through the fancy Windows 10 settings menu

None of this holds forever. It just forgets the file type association at random.

Latest update: KB3206632

Any suggestion is much appreciated.

Have you tried to follow this tutorial?
I pasted the important part below:

How To Change File Associations in Windows 10, 8, 7, or Vista

Note: Setting a program's default file association does not restrict other programs that support the file type from working with them in other situations. More on this at the bottom of the page.

1. Open Control Panel. In Windows 10 & Windows 8, the Power User Menu (WIN+X) is the quickest way in. Try the Start Menu in Windows 7 or Vista.
   See How to Open Control Panel for more details if you're having trouble finding it.


2. 
   

   Tap or click on the Programs link.

   
   
   

   Note: You'll only see this link if you're on the Category or Control Panel Home view of Control Panel. Otherwise, tap or click Default Programs instead, followed by Associate a file type or protocol with a program link. Skip to Step 4.

   
   


3. Tap or click the Make a file type always open in a specific program link, located under the Default Programs heading.


4. Once the Set Associations tool loads, which should only take a second or two, scroll down the list until you see the file extension that you want to change the default program for.



5. Tap or click on the file extension to highlight it.




6. Tap or click the Change program... button, located just above the scroll bar.



7. 
   

   What you see next, and the next step to take, depends on what version of Windows you're using. See What Version of Windows Do I Have? if you're not sure which set of instructions to follow.

   
   
   

   Windows 10 & 8: From the "How do you want to open this [file extension] file from now on?" window you see now, look through the programs and apps in Other options and find, and then tap or click on, the program you'd like to open when you double-click or double-tap these types of files. Try more apps for the complete list.

   
   
   

   Windows 7 & Vista: From the "Open with" window that popped up, look through the programs listed and choose the one you'd like to open for this extension. The Recommended Programs are probably the most applicable, but there may be Other Programs listed too.

   
   


8. 
   

   Tap or click the OK button.

   
   
   

   ​Windows will refresh the list of file associations to show the new default program assigned to this file type. You can close the Set Associations window if you're done making changes.

   
   


9. From this point forward, when you double-click or double-tap on any file with this particular file extension, the program you chose to associate with it in Step 7 will automatically launch and load the particular file.