Good morning, avanstockum.

Thanks for turning to the Community for support. I'm happy to provide some info regarding custom fields in QuickBooks Online.

The QuickBooks Online Advanced program offers the ability to add custom fields to nearly any form you need. These include: sales reps, customer types, vendor IDs, PO numbers, etc.

Here's how to get started:

1. Go to the Gear icon, then select Custom fields.
2. Select Add custom field. If you’ve already created a field, you’ll see Add field instead.
3. Enter the name of the custom field in the Name field.
4. Select the type of data in the Data type ▼ dropdown that will go in your custom field: Text and number, Number only, Date, or Dropdown list. If you select the Dropdown list, enter the items in the list.
5. Select the category the custom field belongs to: Customer, Transaction, Vendor, or Project. Customer fields are for customer profiles, and vendor fields are for vendor profiles. You can assign transaction fields to sales forms (like invoices, estimates, and sales receipts) and purchase forms (like purchase orders, bills, expenses, and checks).

6. Select the forms where you want the custom field to appear. Note: To use custom fields in purchase orders, you need to turn on purchase orders for your company first.
7. If you want customers or vendors to see the field on a form (such as invoices, estimates, or purchase orders), select Print on form. A maximum of 3 custom fields may have Print on form turned on for any single form type (such as Sales Receipt or Invoice).
8. When you’re finished, select Save.

The following article provides additional details about creating and editing custom fields in QuickBooks Online Advanced.

With this info you'll be able to add fields to keep track of your customers data. Please feel free to drop a comment below if you have any other questions.