How to make the featured image smaller

To Whom it May Concern,

I use a wordpress theme called Divi. In divi, when I create a page or post, I can add what are called modules to a page or post. Each module achieves different things.

1 module in particular is called the blog module. When I add the blog module into a page, what happens that it puts all of my posts into an easy to navigate list. One issue however is that the featured image for each post is huge. Here is the page where you can see what I am referring to: http://art2lifeacademy.com/artist-of-the-week-1/

Do you know of a way to make this featured image small, like more of a thumbnail size? I've granted access to my site, so if you have any suggestions please don't hesitate to let me know. This is driving me crazy!

Best, Nicholas