Migrating over from QuickBooks Desktop we recommend that you treat it as a start from scratch setup for Mobius Connect.
The customers, vendors, and accounts map differently.
To make mass changes to fields in QuickBooks Online to match the mapping needed for Mobius, we recommend an app called Transaction Pro.
Below is a video that shows you how you can make changes in your files. You can export vendors, customers or accounts, make changes and then reimport them in. So if you have two fields that are switched, they can be readjusted and then reimport it in.