Hi there,
Welcome to the Community. QuickBooks is a flexible program that makes it easy for you to keep track of your transactions. I'll be happy to provide more info and make sure you're on the right track with your banking.
Based on what you've described, I recommend disconnecting and reconnecting the bank account as the issue may be stemming from the connection. You can also delete duplicate transactions by following the steps below:
1. Navigate to the Banking menu.
2. Click on the For Review tab.
3. Select the checkbox of the transactions to exclude.
4. Hit Exclude.
Give this a try and let me know how you make out. I'll be a message away in case you need additional assistance.