Change color and size: class="av-catalogue-title"

Hey purpleblue_Es,
Please try this code in the General Styling ▸ Quick CSS field or in the WordPress ▸ Customize ▸ Additional CSS field:

#main .av-catalogue-title {
	font-size: 20px;
	color: blue;
}

adjust the color and size to suit, then after applying the css, please clear your browser cache and check.
If this doesn’t solve please link to your page so we can examine.

Best regards,
Mike