I switched to online because my desktop version was being discontinued. How to I get multiple clients' data into this new version?

Thanks for choosing QuickBooks Online (QBO) in managing your business, jgb84025.

If you are using the QuickBooks Online Accountant (QBOA) version, your clients can invite you to become their accountant. This connects their QBO company file to your firm so you can review and make edits to their books. Here's how they can invite you:

1. The client will sign in to QuickBooks Online as a primary admin.
2. Go to the Grear icon on the top menu. 
3. Select Manage Users.
4. Choose the Accounting firms tab.
5. Tick Invite.
6. Enter your accountant's info and press Save.

Then, QuickBooks emails an invite to your accountant where it has steps for how to connect your accounts. If your accountant doesn't have QBOA, there's also a link for how to sign up. If you can't accept their invite or connect their company files, follow the steps and details in the What to do if you can't accept client invites in QuickBooks Online Accountant article to troubleshoot the issue. 

However, if you are using the QBO version, just create or add another company file to QBO. If you have multiple companies under separate accounts, you can move them all into one account. Feel free to visit our Account management page for more insights about running and managing your business in QuickBooks.

I'd like to know how you get on after trying the steps, as I want to ensure this is resolved for you. Please reply to this post and I'll get back to you. Have a great weekend.