In the Cached Web Content section, click Clear Now.
Close the about:preferences page. Any changes you've made will automatically be saved.
Option 3: Use a different web browser
If none of the suggestions above worked, you may need to try a different web browser. Your web browser is the application that enables you to access web pages, so you are currently reading this in a web browser. The buttons below will take you to a website that will allow you to download and install for your computer. You can choose from the download page whether you are using Mac or Windows.