Invoice Notes and Invoice End Notes
1. If you want the note to appear on ALL invoices created after this point go to:
Admin -> Setup Receivables -> Company Options -> Default Values (tab).
Enter your note in the Default Invoice Note field.
2. If you want a specific note on only one Invoice, setup your standard Invoice Notes in:
Admin -> Setup Receivables -> Invoice End Notes.
When you create an Invoice, these notes are displayed at the bottom of the screen. Place a checkmark beside the note you would like to print on this invoice.