You can customize all the text that appear on the invoices (or quotes, estimates, work orders) to your own language or change it to comply with specific needs for your country, for example:
“Invoice” to “Factura” in Spanish
“Invoice” to “Facture” in French
“Invoice” to “Rechnung” in German
“Invoice” to “Tax Invoice”
“Tax” to “GST”
“Tax” to “IVA”
etc...
Go to Settings
Tap Customize Language
In each field enter the custom or translated word
Tap Done
This customization will be applied when emailing or printing the sales documents. The text on the screen will remain the same.