Many users have reported to me that their default browser has changed to Cannot change default browser from TwinUI and they cannot change it back to any other browsers and default programs app just closes.
Here is easy fix just open Windows powershell (you may need to run as administrator) and copy power shell script there.
Get-AppXPackage | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)\AppXManifest.xml”}
Now you can go to Default programs and change it to any other browser.