How can I have different customer messages on different invoice customized templates?

Hi there, Angela.

You can utilize the Message on Invoice text field when creating an invoice for your customers to create different customer messages even when using other customized templates.

If you mean by the body of the email, you'll need to Save and Send the invoice to initiate the prompt to edit the email body and subject. Refer to the sample image below:

Moreover, you can also consider creating recurring invoice transactions in QBO. This way, an invoice will be made regularly at fixed intervals, such as daily, weekly, monthly, or yearly.

Please don't hesitate to leave a reply if you have additional concerns about creating messages for your customers in QBO. I'm always here to support you.