Let me share some information about some limitations when converting to QuickBooks Online (QBO), nakum.khoda.
There's some payroll info that doesn't transfer since Desktop has more payroll features. You can check out the screenshot below for the full details:
For customers, your jobs convert to sub-customers. Then, the entire Ship To Address will be placed in the main address field. While the City, State/Province, ZIP code, and Country will leave as blank.
To learn more about this one, refer to this article: What to expect when you switch from QuickBooks Desktop to QuickBooks Online. Then, go to the Customers and jobs section.
You can check out these articles about importing your data to Online version:
I've got a link here that provides you with articles about getting started with QBO: https://quickbooks.intuit.com/learn-support/en-us/get-started/07?product=QuickBooks%20Online.
I'm just one click away if you need a hand with running your business in QBO. I'm always here to ensure your success. Take care always.