Hi there, Lerco.
Thank you for posting here in the Community. I'm here to help share information about closing QuickBooks Desktop (QBDT).
There are two ways to close QBDT, the first is by clicking on the X button at the upper right corner of the QuickBooks homepage. The second method is by going to the File menu, and selecting on Close Company. Once done, go back to the File menu, then select Exit.
Both ways safely close QuickBooks and the company file, the only difference is, when you close QuickBooks using the X button, once you open it again, QBDT will automatically bring you to the login screen of the last file you've opened. On the other hand, if you close QuickBooks by closing the company file first, you can log in as a different user or switch to another company file.
Please let me know if you have any other questions about closing QBDT, I'm always here to help you. Have a great day ahead!