I am running the latest version of IE. But many websites I visit, including YouTube give me errors saying I'm not using the latest version. Here's YouTube's error "Alert! Your browser is not supported by YouTube and it needs to be updated. It's not just YouTube, many sites give similar errors. Windows says I am running 10.0.9200.16519.
Here's is more info from YouTube:
"You are using an outdated browser, which YouTube no longer supports. Since some features on YouTube may not work, you are viewing a lightweight version of the video page."