Change size of slide

Hi,

I have set a slide for posts above articles on home page, but it’s cropping the featured images. How can I change that ? I already set the “not crop” option for featured image on home page, but it doesn’t change anything for the slide. I don’t mind change the CSS, but if you could tell me what is the code to change, cause all I’m able to do now is change the size, but not the cropping. Thank you !