Hello, EJ.

I'll share the steps in updating a credit card account number in QuickBooks Desktop. 

You aren't missing anything at all. You're right about the process. However, you'll just want to disconnect the connected credit card account and update its number (you don't have to disconnect all accounts). 

Note: QuickBooks won't let you disconnect an account if it has transactions left for review. Categorize them first before doing so. 

Here's a step-by-step process:

1. Go to Lists, then choose Chart of Accounts. 
2. Find the connected credit card account, then right click on it.
3. Select Edit account.
4. In the Edit Account window, click the Bank Feed Settings tab.
5. Tick Deactivate All Online Services. 
6. Hit Save & Close. 

Next, reconnect the account with the correct credit card number: 

1. Go to Banking.
2. Select Bank Feeds.
3. Choose Set Up Bank Feeds for an Account.
4. Follow the on-screen prompts to connect the credit card account again.

When you're done, continue reconciling your accounts. If you need help with the process, I'd recommend reading this article: Reconcile an account in QuickBooks Desktop.

I'm also linking our general support page with articles if you need help with other processes in QuickBooks Desktop. 

I'm all ears if you have other concerns with the program. Just post them here and I'll get right into it. I hope you're having a good week.