Hi Robert,
What have you tried?
Did you try these steps:
Step 1: Open Start menu, click Settings icon to open Settings app.
Step 2: Click System (Display, notifications, apps, power).
Step 3: Click Default apps or search for "Default" and you should see "Default app settings".
Step 4: Go down to video player, click on current default player and then select PowerDVD 18 from the list.
This works for me. Let me know if that helps.
Dave