Can’t edit contend added to cart and during checkout

Hi,

Although I have options and when selected they do add as price in the cart, I cannot change/alter the order.

I have to remove from cart and do it all over again, if I want to simply add/remove an additional item.

In the picture below, I have clean 120 for a book and two fields checked – both equal 36, so the math is correct. However, I cannot do any changes once the item is added to cart.