Cannot Update an Item on another site without updating all items in list

Hi

It seems im missing something here.

I can create an item in another site, but i cannot update only one item in another site.

If i  Use "Update Multiple Items" it gives me the option but then it updates every item in that list.

Im trying to have 2 lists. If i Update  item List 1, it needs to Update item List 2.

Kind regards