Change Header Font - Image Stack

Site URL: https://www.thebowerstudio.com/personalized-cards-how-to

Hello. I am attempting to change the heading font in an image set to "Stack". I've attached a screenshot below.
I'd like to have consistent fonts across our site. We are using Cormorant Garamond, though we also have a custom font called Quincy (which I haven't looked into adding to our site yet). 

I went into site styles and was able to change the Body font for the image stack, but the header font does not change. When the header is selected, the sidebar shown in the screenshot comes up. The upper option supposedly changes the heading font. However, the setting there is for Cormorant Garamond. Despite this, the heading still has a default font.

I'm using the Clay template - Old version (7.1 I think)  I am planning to update to 7.2 eventually, but I'm not certain when. 

Is there code that can be added to change this? Or perhaps another setting needs adjusting?

Thank you!

Add this to Design > Custom CSS

.design-layout-stack .image-title p {
    font-family: 'Cormorant Garamond' !important;
}

Unrelated, I see you mentioned 7.2 version, is there any article about this version?