How do I enter missing transactions from bank accounts in order to reconcile the account in QuickBooks?

Hi there, corradoscanvas!

You can download the missing transactions from your bank's website. Then, upload them to the Banking page, so you can add them to your bank register. Here's an article to guide you with this: Manually upload transactions into QuickBooks Online.

You can also check about bank reconciliation.

Let me know if you need more help.

@corradoscanvas 

Another option, utilize the trial version of SlickConnect. It is designed to import into any bank or credit card in QuickBooks Online, so there is no specific setting needed. 

https://www.moneythumb.com/?ref=110