Manual image size?

I’m using the Hueman theme with a custom thumbnail size of 262×123. This doesn’t work very well with the WP Product Review plugin because by default, the images show up in that thumbnail size. Any suggestions on how to get a more square thumbnail (or just something that looks better) to show in the review box?

A sample review on my blog is here: http://jershaanddup.com/sharp-shirter-pug-gnome-print-review/

https://wordpress.org/plugins/wp-product-review/