When creating an initial account in ACH Universal, it is important to remember that you will be connecting to just one bank account. [File->New Account->Create an account...]
If you need to connect to a second bank account, you will create a second account in ACH Universal.
If you are working with different QuickBooks Online companies, each company must have its own account in ACH Universal as well.
It is important to remember, before switching from one QuickBooks Online company to another in ACH Universal, you must be completely logged out of the first company in QuickBooks Online.