Hi jhikarido,

At the moment we're unable to assign a specific invoice template for customer in QuickBooks Online as this will change all sales forms.  We appreciate if you can send your product feedback. You can do that by going to Gear icon and select Feedback so it will be reviewed by our Product Developers. Most of the new features or product enhancement we release every month are based on the feedback we received from our customers.

For additional information about our current enhancements and innovations, feel free to visit our site at https://quickbooks.intuit.com/au/product-updates/.

Feel free to post again if you have any other questions. Have a nice day!