I appreciate you taking the time to thoroughly explain the issue you're experiencing with your bank accounts, MCWW. Those specifics are so helpful for troubleshooting.

When reconnecting a bank, you'll need to do it in your Chart of Accounts so it will not create a new one. 

This process will ensure the integration stays on the existing account.

For the second account, you can disconnect it since you will be reconnecting the old one. Please note that this process will delete transactions that still need to be categorized in the For review tab. If the transactions are older than 90 days, you won't be able to download them into QuickBooks again.

 Let me share these steps on how you can do it:

1. Go to Transactions, then Bank Transactions.
2. Select the tile for the bank account.
3. Click the Pencil ✎ icon, then select Edit account info.
4. Select the Disconnect this account on save checkbox. 
5. Choose Save and Close.

Once done, let's go to your Chart of Accounts to reconnect the existing account. Here's how:

1. Go to the Accounting menu and select Chart of Accounts.
2. Look for the bank account, then click the dropdown beside View register and select Connect bank.
3. Follow the onscreen instructions to make a connection.

Please be aware that merging accounts connected to Online Banking is not possible, which is why you are unable to do it. You can manually edit the transactions to move them to the correct account and sort out the balances as well. 

Here's an article about this for more details: Merge Duplicate Accounts, Customers, and Vendors in QuickBooks Online.

Never hesitate to ask follow-up questions as we sort out your online banking connections, MCWW. Smooth bank feeds integration is crucial, so I want you to feel fully supported.