1. Open General Settings and the Ordering tab. Select the System Default Order Form Template.
2. Open Products/Services and edit a product group if it needs a different comparison layout. Select its Order Form Template and save.
3. Review the group's headline, tagline and shared features. Check that the selected template actually displays those elements.
4. Open the group in a fresh browser session. Add a product, select its options, view the cart and proceed to checkout.
5. Repeat with a cart containing products from two groups. Confirm consistent totals, payment methods and checkout styling.

A product-group template applies to that group's display and product configuration. The standard View Cart and Checkout steps use the system default because the cart can contain multiple groups. A URL containing a carttpl selection can also affect the template used during the visit, so inspect promotional links when a layout differs from your saved setting.

Verify the template vendor's compatibility with the installed WHMCS version and client theme. Test configurable options, domain selection, tax presentation, coupon errors, login and payment validation. Include keyboard navigation and a narrow mobile screen in the review.

Keep pricing language precise. Customers should see the amount payable now, the chosen billing term, setup fees and the renewal basis before payment. Do not rely on a comparison card alone to communicate conditions that disappear later in checkout.

Keep a versioned copy of custom changes and compare them with vendor changes during upgrades. Use a private test environment to validate updated forms. If checkout breaks after an upgrade, compare with a compatible stock template to isolate the customisation before changing payment or provisioning settings.

• Organize WHMCS products into customer-facing groups
• Maintain a custom WHMCS theme across upgrades
• Run an end-to-end WHMCS test order before launch
• Configure WHMCS promotion codes and eligibility limits

• WHMCS order form templates
• WHMCS product groups
• WHMCS: set up a test environment
• WHMCS: updating WHMCS