Slider with thumbnails – is it possible to resize thumbnails?

Is it possible to adjust the size of the thumbnails for the SimpLy Slider with thumbnails? The current 59×50 size is quite small and looking to increase the size to 124×105 pixels. Everything else works perfectly on this gallery, but the thumbnails could be larger (or have a custom setting?). Thank you!

https://simplygallery.co/simply-slider-carousel-for-wordpress-site/