Hi there, @Ron1996,
There are multiple reasons why a bank balance may not match the register in QuickBooks Online (QBO). One example of this could be an outstanding transaction, such as a check that hasn't cleared the financial institution. In an instance like that, it's generally recommended to wait for it to clear from your financial institution. Naturally, there can be a delay with transactions reaching For Review, due to a person waiting to deposit it and processing times at the bank.
Another reason is deleted or duplicate transactions. Since QuickBooks shows a negative balance, I would recommend looking first for duplicate transactions.
I wanted to include an article that can help guide you in ensuring that information matches between QuickBooks and your bank: How to Fix Differences Between QuickBooks Balance and Bank Balance.
I also recommend the following resource which contains multiple articles to help with this process from start to finish: Reconcile Hub.
Please let me know the outcome or if I can be of additional assistance. Wishing you a wonderful week!