Good evening, @Tom-AFI.
Thanks for taking the time to reach out to the QuickBooks Community for support.
In QuickBooks Desktop, you can add up to 4,000 characters in the description field. However, in doing so, you'd need to manually add the terms each time you create an invoice. The custom fields you can include on invoices can only have up to 30-40 characters at a time.
I understand how beneficial having the option to include more characters in custom fields would be for you and your business. That said, I've gone ahead and submitted a feedback request to our Product Development Team. This way, the suggestion can be considered in a future update.
You can see a full list of character limitations in Character limitations for fields in QuickBooks Desktop.
Please don't hesitate to let me know if you have any questions or concerns. I'm always around to lend a hand. Take care!
