Can you tell me how to change the address on invoice that i have already sent?

Hi rharriselectrica, 

You can change the company address on an invoice by editing the invoice template. To do this, go to the Gear icon > Custom Form Styles > Edit.

From the Content tab,click into the invoice header and select Address to edit. This will automatically update the address on all invoice templates if you have multiple.

To send the updated version to your customer, open the invoice and hit 'Save and send'.

Thanks!