Having trouble switching default apps

I recently bought a cheap computer that came with Windows 10. Mainly using it for basic tasks like writing and web browsing. I've been trying to switch the default apps to some better options. I was able to switch my default media player to VLC but I want my pictures to be displayed by XnView.

When I try to switch the picture default XnView doesn't appear as an option. I only get the original program or Windows insists on me using the store app. I'm having the same problem with a few other default programs.

Is there anyway to force Windows to use the programs that I want?

I presume you're using the Settings app. In which case try changing it in Control Panel.
Control Panel -> Default Programs - Set Associations

If you still can't do it, you're going to need to edit the registry. Which is described here: https://superuser.com/questions/436939/where-is-the-default-program-associations-stored-in-the-registry

I appreciate the help