Cross-sell items appear in the shopping cart, upon checkout. When a customer navigates to the shopping cart (this may, or may not, happen automatically after adding a product), the cross-sells block displays a selection of items, marked as cross-sells to the items already in the cart. They’re a bit like impulse buys at the checkout counter of the department store, or similar to magazines and candy offered at the cash registers in grocery stores.
You may add, edit, or delete Cross Sell products by selecting the relevant option, illustrated below.
If necessary, you can filter your product list by this parameter in the main product page of Store Manager. Just press 'Fast Custom Filter' option in the top toolbar
and you can find the required filter position among the others in the main product filter drop-down menu: