Hello there, iain_brogden.

You can find the email template for statements in the Messages tab.

Here's how:

1. Click the Gear icon, then choose Account & Settings.
2. Go to Sales and then click Messages.
3. Under the Sales form field, choose Statements.
4. Then, enter your default email message for statements.
5. Click Save, then Done.

If you're referring to the email templates on your Custom Form Styles page, it is only applicable for Invoices, Estimate, and Sales receipt.

Feel free to post here again. I'll be around to help.