In DiscountDuck, you can choose the position of all the widgets displayed on your store. This is applicable for Quantity breaks widget and the cart widget.
Change Cart widget position
Open the configuration page of DiscountDuck and click on "Cart widget".
Scroll down and find the section "Widget location"
Click on "Manual location" and then on "Select location"
You will be redirected to your cart page.
Move the mouse on the screen and put the orange square box at the position you want to set your widget and click inside the box.
You will re redirected again to your configuration page, save the settings to validate the new widget position.