Outlook keeps asking me how to open jpg files

[Roman Frantsev]

Hi! This one drives me crazy - every time I try to open a jpg file from my Outlook 2016 (installed on Windows 10 as part of my Office 365 subscription), I get a prompt, regarding how do I want to open this file. Checking the box "always use this app" doesnt help. Opening other files works fine, e.g. for pdf files Outlook uses the Standard app. But for images it just forgets every time.

How do I fix this?

Thank you.

[#2]

@CESDewar I also use Irfanview as a jpg viewer. Nothing listed here has worked. 

[#3]

@Tom_Whitetry the following: go to the "default apps" and below click on "Reset". Then change your Photo viewer back to Irfan.

[#4]

@Roman Frantsev That seemed like a good idea but it didn't work. It still asks me every time if I want to use Irtfanview as the default viewer. The check mark is not recognized.

[#5]

This did it. Thank you.