How do I undo an Always action on a Windows 10?

[Warrior-Phoenix]

I accedently clicked on 'Always use this' box and now every time I click on the file I want it opens on that. Please help, I would like to undo the problem.

Thank you.

 

[bjornl]

here you go:
http://www.digitaltrends.com/computing/how-to-set-default-programs-and-file-types-in-windows-10/