https://wccftech.com/windows-10-bug-unable-apps-defaults/

Another week, another Windows 10 bug to report. The re-release of the October 2018 Update (or what should now be called a November Update) is yet to begin, but it appears Microsoft is dealing with a growing number of problems that are plaguing older versions, as well. The company is having a hard time dealing with Windows 10 bugs lately, and there is a fresh headache to add to that growing list of issues.

New reports suggest that the entire file association system is messed up after a cumulative update was sent out last month. Apparently, the operating doesn’t let you select certain applications as your default options. The issue was tested by the folks at HTG who report that after testing the issue on multiple machines running Windows 10 April 2018 Update, they can confirm that every PC has this problem.