Open Yahoo Mail in a web browser
Sign in to your Yahoo account
Click the Settings gear icon
Look for a Mail version, View, or Switch to basic mail option
Select the older or basic version if available
If no switch option appears, use a browser that supports the older interface better
Clear your browser cache and reload Yahoo Mail
Disable browser extensions that may affect the page
Try accessing Yahoo Mail from another device or browser
If the old version is no longer available, use the current Yahoo Mail interface