Go to the North America section, then click the United States.
Select whether to subscribe now or use a 30-day free trial and the type of subscription you will be using.
Click Add another company, then enter your existing Intuit login credentials.
Follow the on-screen instructions to set up the account.
Once done, let's try to import your customer, suppliers, chart of accounts, and products and services list from the old account. For more detailed information about importing, you can check out this article: Export Then Import List Data Into QuickBooks Online.
If you ever have other questions we can help you with, feel free to swing by the Community!