Hey there, vicki26. Let me provide some steps for setting up your ACH in QuickBooks Online (QBO). 

Before setting up your ACH in QBO, make sure you have a subscription either in QuickBooks Payments or QuickBooks Bill Pay. Know that QuickBooks Payments is for the Customers and Bill Pay is for the Vendor. Right after, you'll have to link these to QBO in your Settings. 

Here's how: 

1. Go to the Gear icon located in the upper right corner. 
2. Under the Your Company columns, select Account and Settings. 
3. Click the Payments section. 
4. Within the Payments tab, you'll see the plan you've subscribed to, click Connect. 
5. Follow the on-screen instructions. 

Furthermore, you can refer to this material in case you want to process an ACH bank transfer for your customers: Process an ACH bank transfer from a customer in QuickBooks Online. 

For further assistance, please enter it in the comment section. Have a nice day and stay safe.