Want the old Yahoo back? I've messed around with the URL a bit, and I found the way to get back to the original.
Instead of typing just
www.yahoo.com in URL filed, type the following, and you will be directed the original page:
http://www.yahoo.com/?q=+client=firefox
However, should you click any links on the Yahoo page that lead to another Yahoo page, they will revert to mobile. It's a pain, but add
?q=+client=firefox on the end of the URL.
- John