How can I add transactions manually if they will not import?

Utilize the trial version of MT Online to isolate the issue. It is designed to import into any bank or credit card in QuickBooks Online, so there is no specific setting needed. 

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Let's make sure you'll be able to add transactions in QuickBooks Online, usermangaboos.

Are you getting a specific error when trying to upload transactions to your bank? Generally, the only way wherein you can add missing transactions is by updating your bank manually or manually uploading it in QuickBooks. To manually update your bank, follow the steps below: 

1. Go to the Banking tab.
2. Select Update.
3. If asked, enter your Multi-Factor Authentication (MFA). Then select Continue update.

On the other hand, each bank formats CSV files differently. Also, the maximum file size is 350 KB. If the file is too big, shorten the date range and download transactions in smaller batches. You may encounter issues when trying to manually upload transactions from your bank, learn more about CSV formats to successfully import the transactions. I've added this article for more details: Format CSV Files in Excel To Get Bank Transactions Into QuickBooks. 

In addition, to know more details on how you can match transactions with those you've already entered in QuickBooks, I've added this article for your reference: Categorize And Match Online Bank Transactions In QuickBooks Online.

Reach out to us if you have any questions about adding transactions. We're here to make sure everything is covered for you.