I can share another way to accomplish that, BevanandTina.

Each text field in QuickBooks Desktop has a maximum number of characters that can be entered. For custom fields, you can only input up to 30 characters. To more about this topic, you can read this article: Character limitations for fields.

I'll also take note of your ideas and suggestions to help improve your experience in the program. In meantime, you can directly enter the additional information of the job in the Memo field of the invoice. This field can contain up to 4095 characters. Here's how to do it:

1. Go to the Customers menu.
2. Choose Create Invoices.
3. From the Customer: Job drop-down menu, select the appropriate customer name or job. 
4. Fill in the relevant information at the top of the form like the Date Invoice #, Bill to/Sold to, and Terms.
5. In the detail area, enter the items and services.
6. Enter the additional details of the job in the Memo field.
7. Click Save & Close.

I also encourage reading this guide to earn about the maximum number of list entries you can make in QuickBooks Desktop: Maximum number of list and custom field entries.

Fill me in if you need further assistance in managing your sales forms. I'll be right here to continue helping.