Product options are shared between products. If you don't want to share an option between products, you can just to create a new one (which can even use the same name) and use it for other product(s).
For instance you could have:
- Product option 1, name "Size", with choices S, M, L
- Product option 2, name "Size", with choices L, XL, XXL
And then:
- Product 1 uses "Product option 1" and so the available choices will be S, M, L
- Product 2 uses "Product option2", and so the available choices will be L, XL, XXL
- Product 3 uses "Product option2", and so the available choices will be L, XL, XXL
If you change the choices of "Product option 2", for instance to L, XL, XXL, XXXL, then both "Product 2" and "Product 3" will be updated and have these 3 choices available. If you don't want that, you could create a new product option for "Product 3".
Related questions:
> When I add variations for products it is changing all the variations previously added to thee other products such that thee same variations appear on all the product listings
> if I get variant with colour. It does not pick one item I like only. It seems to share one colour with the other product as well.