Change your Order Form Template
To change the default order form template to be used by the system for product selection, configuration, view cart and checkout stages in the event that no other template is specified:
Navigate to Configuration > System Settings > General Settings (prior to WHMCS 8.0, Setup > General Settings).
Select the Ordering tab.
Select your desired order form template from the Default Order Form Template section.
Changing the order form template for a product group
A different order form template can be selected for product selection and configuration stages of the ordering process. This is done on a per product group basis.
Navigate to Configuration > System Settings > Products/Services (prior to WHMCS 8.0, Setup > Products/Services > Products/Services).
Click the Edit icon next to the product group you wish to edit.
1. In the Order Form Template section, select the Use Specific Template option
2. Select your desired order form template
Finally click Save Changes.
The selected order form template will now be used for the product selection and configuration stages of the ordering process whenever a product within this product group is selected.
The System default order form template will be used for the view cart and checkout stages of the order process.
For more information on Product Groups, please refer to http://docs.whmcs.com/Product_Groups