Hello @KarenSOS,
Since you're still unable to determine why your check transaction number is changing after importing IFF files, let's consider integrating one of our third-party apps to help you with the import.
But please know that we're unable to provide the specific app you can integrate with. And we're also unable to answer any app-related questions such as how the app works. Thus, I'd recommend contacting the app provider first before integrating it into QuickBooks.
That said, here's how you can integrate an app:
- Go to App Center.
- Enter Import IIF Files in the Search field.
- Select the app you wish to integrate and check for reviews.
- Click Learn More.
Additionally, I've also included this reference for a compilation of articles you can use while working with us; Help Articles for QuickBooks Desktop.
If there's anything else that I can help you with, please let me know in the comments below. I'll be here to lend a hand.