You can customize a sales receipt and change the form name into Service Invoice, office322.
Please note that if you create a template to rename the form from Sales Receipt to Service Invoice, the changes will only appear when printing or emailing the receipt.
Here's how you can create a customized template:
- Go to Settings and select Custom form style.

- Click the New style button and choose Sales Receipt.

- Rename the template to Service Invoice (or any name you'd like).

- Click the Content tab and select the first tile.

- Under the Form section, edit the Form name and change it to Service Invoice.

- Click Done.
To apply the template to your sales receipts:
- Open or create a Sales Receipt.
- Click Customize and select the template you created.

- Hit Save.
Once completed, you can check the form by clicking the Print or Preview link, where it will display as Service Invoice.

Don't hesitate to reach out if you need any further assistance.