Featured image sizing problem

I searched and saw a couple people using different themes having the same problem, but none of the solutions seemed to work for me on the High End theme. I have a featured image set for a post (so it will show on the home page which is set to “latest posts”) but despite resizing the image, it still appears extra extra large (larger than I resized it to) on the home page and I can’t get it to change. Help appreciated, thanks!