To use the latest version of the Simplify feature, you'll need to update your Read&Write for Google Chrome extension.
To update your extension, follow the steps in How to Update Read&Write for Google Chrome
If Read&Write has been force installed to your domain or you can't manually update you extensions, contact your Google administrator for help.
To use the latest version of the Texthelp ePub Reader, please use epub.texthelp.com.
Users from the legacy ePub Reader please see Using the Texthelp ePub Reader.