The shopping-cart is managed by Caddy - responsive e-commerce with TYPO3.
You can control some properties of the shopping-cart by the Caddy user-interface.
Each page, which displays the cart, contains the Caddy user-interface.
Please select this user-interface - called plugin - and change the properties for your needs.
The user-interface should be self-explanatory.
Precondition for a proper running Caddy plugin is a proper TypoScript-template.
It is the job of your TYPO3-integrator, to take care of this proper TypoScript-template.