Customers have experienced sudden shrinking of the screen for Yahoo mail that users are barely able to read the content. This issue has been more prevalent with Firefox users. In such a situation, the users are requested to click on blue square which is located on the top right of the email screen. This is nothing but the set of default screen which brings back the screen to the normal size. Apart from that, users can also increase the font size of the email content by clicking on view tab and adjusting the font size. In such cases, customers can also seek guidance from the customer service yahoo mail 24/7 help team requesting for their help.