Customise sales invoice header to 'TAX INVOICE'

I was using an older version of manager and was able to put custom sales invoice header text. My clients want the invoice header written ‘Tax Invoice’ instead of just invoice. i updated to version 18.5.9 and i cant see where to customise this. please help!

You must have been using a really old version. You have not been able to specify the invoice title directly for years. And you are already 23 updates behind. Manager advances very rapidly.

When a country tax code is used for a jurisdiction where Tax Invoice is the required title of a sales invoice, Manager automatically makes the conversion.

If local law does not require the change, but it is only a matter of preference, you can change headings with a custom theme. See this Guide: https://guides.manager.io/7877.