Welcome to the Community, @TurkishCarpetsInc.

I also want QuickBooks to allow this as much as you do. I know how advantageous it is for you and other users to add Custom fields to your Products and services to further describe the items you offered in QuickBooks Online (QBO). However, it is still unavailable in QBO.

You can only have up to 12 active custom fields for each type of form (invoice, estimate, purchase order, expense, bill, and so on), and each type of profile (customer and vendor).

With that, I recommend leaving feedback to notify our software engineers about the feature you need. In this way, they can take it into account for future product improvements.

To send your input, here's how:

1. Open your QuickBooks Online account.
2. Go to the Gear icon and select Feedback.
3. Type in your suggestion and click Next.

Kindly refer to this article to learn more about custom fields in QBO: Add custom fields to sales forms and purchase orders in QuickBooks Online.

Moreover, I'd also like to share this link that can serve as your reference where you can search for articles that can guide you in managing your QuickBooks account: QuickBooks Online Help Articles.

Feel free to leave a reply if you have additional queries about managing your QBO account. The Community team always has your back. Have a good one.