Resizing Images in Weblizar slider

I am a total newbie to all this and would like to resize the images in the slider on the main page of weblizar, at my site https://www.mishpahah.org. The images are way too stretched. When I tried a few other templates the images were perfect and not so stretched. How can I fix that? (I have already made several alterations in image sizes, but nothing has changed and I will not remember all the ones that would need to be switched back.)