If only. Windows 10 has this annoying habbit of changing the defaults after updates. It's so frustrating that I would never choose Windows 10 for dev work unless I had to.
When I click the little quotes that pop up on my login screen after the creator's update it always pops up in Edge instead of Chrome even though Chrome is my default browser.
Do this:
1. Go to Windows Settings -> Apps -> Default Apps
2. Scroll down and select "Set defaults by app"
3. Choose IrfanView and then "Choose defaults for this program"
4. Select all the file types you want associated with IrfanView (JPEG, PNG, GIF, etc).
5. Click Save.
That should do it.