Welcome to the Community, @Gracias1234.
I appreciate you letting us know about your business needs. Currently, you can only add up to three custom fields on the sales form. If you'd like to include other information, you may add them to the Message on invoice field.
We always value customers who are keen to give us their feedback, especially if it's something you'll need for your business. That said, I'm here to help pass this along to our Product Team.
In the meantime, you can visit our QuickBooks Online Blog to know more about our latest happenings. From there, you'll get the latest news and updates about QBO and what our Product Team is working on.
If you have other questions, please don't hesitate to let me know. I'll be here to help however I can. Have a good one.