Thanks for joining this thread! I'll help you clear things up @bee_dee. 

Before so, I'd like to know the name of your bank institution.

When you disconnect your bank account in QuickBooks Online (QBO), you'll no longer see transactions in the For Review section, except for those categorized. 

If you reconnect it, the transactions older than 90 days won't be able to be downloaded from your bank. Instead, manually upload old transactions in QBO. 

Here's how: 

1. Select Bank transactions from the Transactions tab.
2. Choose the tile to which you want to upload the transactions.
3. Click Link account, then select Upload from the file. You can use either the 3 or 4-column CSV format.
   
4. Pick the account you want to upload the transactions from the QuickBooks account. Then, Continue.
5. Follow the onscreen steps. Select the transactions you like to import and click Continue.
6. Select Yes. Then, Done.

You might want learn how to categorize your bank transactions automatically in QBO. Consider checking this article. : Set up bank rules to categorize online banking transactions in QuickBooks Online.

Feel free to reach out to QuickBooks Live Expert Assisted to further streamline your bank categorization and guide you to any banking-related task.

You can leave a comment below if you have additional questions.