Invoices are generated as PDFs and remain persistent based on the original event settings. If you make changes to your event settings and need this reflected on previously issued invoices, you can regenerate the invoice PDFs via this tool.

Note that once changed, the changes will be reflected across all invoices generated between the chosen date range.
If you need to change the info of a single invoice to reflect a change in contact details, you should regenerate the invoice in the relevant reservation record only.