Selecting / Cropping images used for blog entries on main page

https://ajourneyawaits.wordpress.com

Hello,

I need some help figuring out how to select which images from my posts are cropped and featured on the homepage. If you go to my blog (oh how I would appreciate someone taking the time to do this so very much !) You will see that there are no images featured on the main page from my latest posts which I can’t seem to change, but if you scroll down, you’ll see it has randomly cropped some of the photos from previous posts in a really inappropriate way that I have no control over. It’s really bad and I cannot figure out how to change or control this. I would greatly appreciate any help.

Thank you so much!

Jackie