Instructions on how to update your web browser can be found below.
Mozilla Firefox generally updates automatically, but you can install updates manually as described on this page: https://support.mozilla.org/en-US/kb/update-firefox-latest-version
Google Chrome's update instructions can be found here: https://support.google.com/chrome/answer/95414?hl=en
Apple's Safari browser updates are a part of OS X updates. For information on updating OS X or applications on your Mac, please visit this page: https://support.apple.com/en-us/HT201541
Microsoft Edge updates are a part of Windows 10 updates. For information on choosing how updates are installed, please refer to the following page: http://windows.microsoft.com/en-us/windows-10/getstarted-choose-how-updates-are-installed