Hello, @tsamop. I'll provide information about the Custom Field feature in QuickBooks Online (QBO).
Currently, the Custom fields feature is available to users with QuickBooks Advanced, Essential, and Plus subscriptions. If your QBO plan is either of these three and you're still unable to access the Add Field button, I'd recommend contacting our Customer Care Support so they investigate what's causing this issue.
However, if you're using Simple Start, you may want to consider upgrading your account to a higher subscription.
Here's how:
- Log in to your QBO company.
- From the Gear icon, select Subscription and billing.
- Under your QBO Plan, choose Upgrade your plan.
- Choose from the available plans and click Choose plan.
- Follow the onscreen steps.
I'm also adding this article for smooth sailing management of your customer's invoice payments: Record invoice payments in QuickBooks Online.
Should you need further guidance on accessing the Custom fields in QBO or any other concerns with your invoices, our team is more than happy to help. Have a good one.
