Hello, gamblelynn.
You're correct. The online version of QuickBooks since it's a cloud base and more on automation. While QuickBooks Desktop is a traditional software that you download and install on your computer. Since the two versions are independent of one another and have different features, some data may not sync between them.
Install the program on your PC to be able to open your QBDT backup file. Could you tell me what version your QuickBooks file is? Since if you still have the license and product key of your QuickBooks software, you can still download and install it. Use this link to download the software: https://downloads.quickbooks.com/app/qbdt/products.
Once you get the installer, install it by following the instructions in this article: Install QuickBooks Desktop.
Furthermore, online is best suited for businesses that require real-time collaboration and the file may be accessed from any device. With this, it isn't possible to change QuickBooks online to look like QuickBooks Desktop.
I've also added some resources below to more about the difference between these two platforms:
If you have further need further assistance with managing your data, let us know. We're available to help you.
