Variable Product, auto change fields

Hi, I have a few products, screws and bolts, that I would like to group together. My idea is that they can choose between one of the variables and then all the others will change automatically, but idk why it doesnt work.

Ive followed this Woocommerce guide, but something doesnt add up.

Heres a picture. As you can see, it forces me to pick every field even though theres only one attribute to each variable. Or is there a better solution to do this? I have 50 different screws and it feels unnecessary to create a product for each one of the different dimensions.