Michael is getting a message from Yahoo that he will lose access to his account if he continues to use Internet Explorer 11. Leo says that's the most recent version so that doesn't make any sense. But if Yahoo is not going to support Internet explorer anymore, then what may be happening is that Robert has compatibility view on. Michael should go into IE Tools and uncheck "use Microsoft compatibility lists." That will send a mixed message to Yahoo that he's using the wrong version.
But Yahoo is also no longer supporting IE. So his choices are Google Chrome or Firefox. Leo says Chrome is actually a better browser security-wise, and it's easy to learn. He can even import all of his bookmarks directly into Chrome. So he really won't lose a step by making the change.