To define in Windows 8 / 10 or 8.1 a file type associate to open with multiple programs or apps, please open the "Default Programs" settings!
Please use the key combination [Windows Logo] + [R] , then just type the command
control.exe /name Microsoft.DefaultPrograms /page pageFileAssoc or open default programs and tap or click the text "Associate a file type .... a program"
See : ... How to open and change default programs settings in Windows 8
Click the Fileextensions [... see Image 1 Arrow-1] and Change program... [... see Image 1 Arrow-2]
See also: The wrong program opens a file in Windows-8?
If you want to choose which file types and protocols a program uses by default, tap or click choose defaults for this program. Note, if a program doesn't show up in the list, you can make the program a default by associating a file type or protocol with it.
Use this option to fine-tune default programs based on the file type or protocol. For example, you can have all jpg image files open, using one program and bmp image files open, using a different program.
FAQ 74: Updated on: November 27th 2015 18:39