2. Find the sprocket icon on the top right side of the page, next to your name. Click it to show the menu.
3. Select "Mail Options". It should show the General options panel. If it doesn't click "General" on the left.
4. Scroll to advanced settings and set the "Switch now" button to "basic".
5. Click "OK" to the dialog box, then click "save at the top".
Refresh the page and you are again on classic yahoo :)
In IE 10, activate the Tools - "Compatibility View" Feature. I realized this was an option after visiting Yahoo Mail on an old XP Machine and seeing the Classic - a huge improvement over this new nonsense!!