If you want to configure a project so that the same memo is added to each invoice, you must add the project rule 'Use project memo on invoices'. This rule adds the project memo on all future invoices of this project automatically. However, in case of phased projects, you must add the memo on the project phases, not on the parent project.
However, if you have selected the Use project memos on invoices rule for all the phases of a project, but want the memo of each phase to appear under it on a joint invoice rather than them being clubbed together at the top or bottom, you can do this by using a custom invoice template. Please consult our Custom Reports Team to explain your requirements and get a quote on it.
Project memos show up in the Memo 2 field of invoices if you have the project rule Use project memo on invoices and the global-level rule Show project memo on invoices at the bottom in Settings > Billing & Invoices > Invoice Settings turned on. If only the project rule is active, the project memo is brought forward to the Memo 1 field.
You also have an option to set the Message on Invoice on the Projects > General > Billing Options tab. Just enter a standard message to print on all invoices of the project. This message displays above the footer of the invoice. You can also set an invoice message at the global level (Settings > Billing & Invoices > Invoice Settings).