Each layout container has custom class: 'image-button-container' applied to it for better responsive breakdown. This is optional but recommended when using throughout your website.
You can copy the layout with the custom image buttons from here and paste them onto your site to ensure proper display. Remember to consider using appropriate amount of description text depending on the context of the button. (i.e. less text for a four column layout than a two column layout etc)
All Content is updated within the element settings. The Title, description and link are the possible fields. The description text (element settings > design > header content area) and the link (element settings > design > footer content area) are both optional.
Once the buttons have been edited, toggle 'compose' mode off and refresh your browser window if you wish to preview them before publishing. Refreshing your browser when toggling 'compose' mode on and off is recommended.