How do I pay a bill that is set up for ACH.

Hello there, @gokeyandmarkle.

Let me help you post the payment to your QuickBooks Online.

Still, by following the standard procedure, we can record a bill payment to an open bill.  Here's how:

1. Select Expenses from the left panel.
2. Navigate to the Vendors section.
3. Simply click on the vendor's name.
4. Select the Transactions tab.
5. Make a payment on the open bill by searching for it.
6. Select the bank under Bank/Credit Account.
7. Remove the check mark next to Print later in the right corner.
8. Enter something in the Ref no. field to help you identify the payment method (ex. ACH).
9. Complete the required fields and click Save and close the window.
   

For more information on recording the bill payment made through ACH, you can visit the article I recommend on this: Record a bill payment processed online, via EFT, ATM, or debit card.

If you're using QuickBooks payments, typically it takes 1-5 business days to process, depending on the financial networks involved. Customers that are new to QuickBooks Payments and have an active account are eligible for next-day ACH deposits.

•  Accept ACH payments and eChecks.
• Process ACH bank transfers right in QuickBooks

For other concerns, please reply again to this thread. Take care always.

@gokeyandmarkle 

Another option, open a separate Melio account for free and integrate it with QBO.

https://melio.grsm.io/quickbooks