What does 'Advanced settings' mean?

By clicking on the 'Advanced settings' button, you will be given the opportunity to manually change some preset settings.

By activating the settings, you can change the following:

Underlined links. By default, they are not underlined, but you can change this by selecting "Yes" or "No".
Image layout - removes margins around images in, for example, Gmail.
Global link colors allow you to manually specify color codes according to your preferences to match your graphic profile.