Hello there, @Rapidcleaning. I want to ensure that your issue regarding online customer payment will be sorted out.

To start, we have to make sure that you've signed up for QuickBooks Payments service so you'll able to process customer payments online. You can verify it on the Accounts and settings page. Here's how:

1. Select the Gear icon and choose Accounts and settings.
2. Next, click the Payments tab.
3. From there, check if you see your Merchant details. 

Once confirmed, we can perform some troubleshooting steps to determine if the error you get is a browser-related issue. We can start with running your account via incognito mode since this does not store cache files that might cause odd behaviors when running web base programs. Below are the shortcut keys you can use:

• Google Chrome: press Ctrl + Shift + N
• Mozilla Firefox: press Ctrl + Shift + P
• Microsoft Edge: press Ctrl + Shift + N
• Safari: press Command + Shift +N

Once signed in, open your customer profile again and edit the payment details. From there, check if you can now select the ACH without issue.

If this works, go back to your regular browser and clear the cache to eliminate piled-up files that might cause the error. If the same thing happens, I recommend reaching out to our Merchant support team to further investigate the issue. They can pull up your account in a secure place and help you get rid of the error. 

For reference, check out this article: Take and process payments in QuickBooks Online with QuickBooks Payments.

I'm always here ready to lend a hand if you have other concerns managing your customer's payments, please don't hesitate to leave a reply below. Have a good one, and stay safe.