Hi,
VirtueMart Dropdown Shopping Cart Module is a module.. Modules are effective only within the module positions. They can't influence to anywhere else.
"Agree terms & conditions tick box" is on the "Shopping Cart Page" and it is part of the page (not module).. If you are using a Joomla Template that supports Virtuemart page styling, then contact the developer of your template. Because this related to Virtuemart Template Overriding..
Regards.