We can make sure that your Merchant account is active, mj20. 

It's possible that it was inactivated that's why you're unable to add or edit your customer's bank information. Let me show you how: 

1. Go to Gear icon and click Account and Settings. 
2. From the left panel click Billing & Subscription. 
3. Look for QuickBooks Online Payments and check if it's active. 

If you get the same thing though you tried adding or editing it after doing the browser-troubleshooting steps and you're Merchant accounts is still active, I suggest reaching out to us. Our Customer Support Team can investigate it further and can open a new case so our engineers can closely look into your account. 

Here's how: 

1. Go to the Help icon and click Contact us. 
2. Enter your concern that you're unable to add/ edit, update and use the payment method in your customer's profile. 
3. Click Let's talk and select a convenient way for you to connect with us like chat or call. 

I'm here if you have further questions.