Note: The background colour of the title and text is controlled via CSS. If you would like to change the colour find the following section of CSS is the Custom CSS box of the parent row:

.bb-cta-infobox-1 .kt-infobox-textcontent {
position: absolute;
    bottom: 30px;
    left: 0;
    right: 0;
    z-index: 3;
background: var(–global-palette7);

Change the background variable colour value.