Because the cart consists of many buttons, some of the parameters have to be set separate from the individual buttons. These parameters are available via the cart's Menu Item.
Create a Easy PayPal Button Cart menu item as you would any other menu item in Joomla. Make sure there is only one EzPPb Cart menu item that is published at one time. Within the menu item, you'll see the parameters to be configured. Leaving these parameters blank will cause EzPPb to use any default settings you may have set in the components parameters (Joomla 1.5) or Options (Joomla 1.6+).
In the cart parameters, you can set cart wide discounts, taxes, and handling fees. Note that setting some of these will override the associated settings for individual buttons. You can also set a return and cancel URLs and checkout page settings. The cart only has visual settings that affect PayPal's new checkout page.
You can set a specific cart merchant ID via the component's parameters/options. If left blank, the default merchant ID will be used.
Read the parameters description in the tooltip when you hover over the label for more information on the specific parameter.