It is possible that you wish to change the contact person (attn) on the invoice.
If you are working on the invoice, you can change the contact details using the pencil icon in the top left-hand corner.
Then use the dropdown menu to select the right contact person.
Rodeo shows all contacts added under the contact.
If the right contact is not listed, it must be first added under contacts.
You can read more about adding contacts here
The selected contact will be shown as attn.
If you want to send the invoice, you have the option to add multiple billing addresses.