If you want to have some extra information in your invoice's receipt, you can insert your text in "Invoice Remarks". Do remember it can be printed out.
1. Create a new invoice and key in all needed informations.
2. You can see "Invoice Remark" at the bottom.
3. Insert the information you want and you can style it too. Or add in images.
4. When you click "print", it will be shown above signature part.