I know how important it is to use an accounting software that you're comfortable and confident with. I can appreciate that you'd like to move back to QuickBooks Desktop after moving to the Online platform. I'd be happy to explain the process and limitations in doing so.
While you're able to export and import a few lists, the complete migration of your QuickBooks Online file can't be moved into QuickBooks Desktop the same way as you can move from Desktop to Online.
I know this isn't ideal, and I want to make sure you're given all the best advice for your business. If you have any other questions, I'd encourage you to reach out to our tech support team.