how do I add a purchase order number to the invoice template

Hello, Boxless.

You can utilise the custom fields to add the purchase order number on invoices. To add a custom field:

1) Click the Gear icon, and then select Custom Form Styles.

2) Create or edit a template for invoices.

3) Click the Content tab, and then click the first section on the preview image.

4) Click the + Custom field link.

5) Check one of the boxes and then name it (let's say Purchase Order Number or PO number).

6) Click Done.

When you create an invoice using the template, you can add the purchase order number manually in the custom field box.

That'll do it. Please let me know if there's anything else I can do for you.