Medium height slide show cropping images

Site URL: https://www.firstclasssportingmemorabilia.co.uk/

Hi I’m new to all of this website building and I’m just  setting one up for a new business of mine I’ve got the slide show effect working well on desktop and managed to code it for mobile looking good, one thing I can’t get my head around is I want to reduce the size of my slideshow on desktop to half the size, but regardless what size I reduce the uploaded photo by it just keeps cropping it out majorly how do I resolve this 

Hi,

What is password?