Mozilla CEO Chris Beard has written an angry open letter to Microsoft CEO Satya Nadella regarding a change to Windows 10's default application settings. Apparently, if you aren't careful when you upgrade to Windows 10, the upgrade process will change the default browser to Edge without asking.
In his letter, Beard calls on Microsoft to revert those changes to the upgrade process. Beard says these changes "throw away the choice [Microsoft's] customers have made about the Internet experience they want, and replace it with the Internet experience Microsoft wants them to have."
Fortunately, changing your default browser back to Firefox isn't difficult. The first time you launch most any web browser, it offers to make itself the default. When you answer in the affirmative, the Default Apps screen opens, and you can choose any web browser—not just Firefox—to be your PC's default. Mozilla has posted an illustrated guide to switching your default browser by launching Firefox.
According to Ars Technica, the Windows 10 upgrade routine does allow you to keep your default applications, but that's not the default behavior. You need to click at least two obscure buttons to manually select your default applications instead, which is kind of onerous. In a statement to Ars, a Microsoft representative indicated changes were possible, saying, "As with all aspects of the product, we have designed Windows 10 as a service; if we learn from user experience that there are ways to make improvements, we will do so."