Source:Microsoft has confirmed that the latest Windows 10 cumulative update, KB3135173, resets the default apps after installation, and it looks like future updates will do so to after deployment.
And the company has a reason.
It’s not because Redmond wants its programs to be used again by users — programs including the brand new Microsoft Edge web browser. Apparently, it all comes down to the fact that it spotted some third-party tools messing with the system.
Windows 10 Cumulative Updates Will Reset Default Apps - Windows 10 News and Updates