Why isn't my product variant selection updating correctly?

So my store has many different products and variants for each product however when my customers are selecting lets say a medium - orange screen it is not updating and making them order a small black one.

my store is at - https://thesteelgallery.co.uk/

if anyone could take a look at it and help me out it would be seriously appreciated as we are now losing money because of this.

many thanks in advance!

Hi @TheSteelGallery

Could you please elaborate as I am not able to found issue please provide the url of product that creating issue.