Crop Thumbnails on Index Page

I’m trying to figure out how to control the crop on the featured/thumbnail images that accompany the post excerpt on the index page. I have adjusted the excerpt-thumbnail in Iconic One to be 1:1 (150×150). In the Media Library, I have cropped just the thumbnail to show only a section of the image. What I hoped to be able to do was have the cropped thumbnail as it appears in media library used on the index page, but this isn’t happening. I get the thumbnail of the correct size, but it’s always a center crop of the original image, not the image thumbnail.

Don’t know if I needed to, but I did regenerate thumbnails after cropping in the media library. I also cleared the browser cache (working on Mac-Safari) Should I be able to make this work the way I want? Is there another approach?

Thanks.