Hello, The Web Decor,
It is because attributes and variations for variable product functionality come not from the theme, but from WooCommerce plugin.
Storefront theme is a free official theme of WooCommerce, you need to test how it works with this theme, to find out if our theme is the reason for not applying re-ordering for variations, or you will need to contact WooCommerce support.
We hope it is clear now.
Kind Regards,
8theme team