PC users who upgrade to Windows 10 may find that Chrome or Firefox is no longer the default web browser.
To set Mozilla FireFox as the Windows 10 default web browser, follow these instructions:
https://support.mozilla.org/en-US/kb/how-change-your-default-browser-windows-10
Some general instructions on how to set Google Chrome as the default Windows browser:
https://support.google.com/chrome/answer/95417?hl=en