Hi,
I checked on your website and you have that CSS code:
#hikashop_show_cart_form .hikashop_header_buttons {
display: none;
}
in the file /templates/ja_simpli/css/template.css of your website which removes all the toolbar buttons of HikaShop on the frontend.
You should remove that CSS if you want to be able to use the interface properly.
Then, the interface will look like that:
monosnap.com/file/Ktm8PSmk88jDmsosJkVlJGqItLJpSq
And you'll see the "save" button to take into account the changes you make to the cart.
I would also recommend contacting your template provider. Because that CSS shouldn't be there. It renders the frontend interface of HikaShop's control panel almost useless.