Hi there, @wsb64.
Please know that displaying the remaining credit limit of a credit card isn't possible in QuickBooks Online (QBO). You can manually go to your Chart of Accounts (COA) and check your remaining balance. I'll guide you on how:
- Open your QBO account and select Transactions.
- Choose the Chart of accounts.
- Locate your credit card and hit View register.

Moreover, you can set up and track the things you pay with your line of credit and record it as a bill or expense. Refer to this article for more information: Manage a line of credit in QuickBooks Online.
For future use, here's a guide on reconciling to ensure your QuickBooks accounts match your real-life statements: Reconcile workflow.
Let me know if there's anything else you want to ask regarding the unused balance on a line of credit in QuickBooks. The Community team is always around to help.