Hi SiobhanRigsafe,
Thank you for your response.
You can edit the details of an invoice from the invoice page or from the sales settings. If you want to change the invoice layout and template, see Sales Settings. Please refer to this Help article, which has detailed information to assist with this.
Please let me know if you still require assistance with this. I'm happy to help.
Otherwise, if my response has answered your question, please click on "Accept as Solution" to help other users find this information.
Cheers,
Princess