How do I change my direct debit to. A new account?

You'll have to edit your direct debit information from the Billing & Subscription page, @sam-finnigan-hot.

You can easily update your bank account for the direct debit to pay your QuickBooks Online (QBO) subscription. When you subscribe through a web browser, go to the Payment method section to complete this process. Please log in to your QBO account as a Master or Company Admin before performing the steps below.

1. Go to the Gear icon.

2. Select Account and settings.

3. Go to Billing & Subscription from the left menu. 
4. In the Payment method section, click the Edit (Pencil) icon.
5. Choose Direct Debit. 
6. Update your bank account info. 
7. Make sure the Billing Address in QBO is the same as the one on your bank statement.
8. Click Save.

I've attached a screenshot below that shows the last six steps.

In case you've subscribed to QBO through the app store, you can change your payment info specific to the phone model you're using. For App Store (iPhone or iPad), perform the steps below: 

1. Go to your device’s Settings menu.
2. Select iTunes App Store.
3. Choose your Apple ID and View Apple ID.
4. Enter your Apple ID password.
5. Click Manage under Subscriptions. 
6. Select your QBO subscription and make the necessary changes.

For Google Play (Android), you need to open a web browser. Then, sign in to your Google Wallet account and select Payment methods. Locate the direct debit account you want to update and click Edit. Input all the necessary information and then select Save. 

There are other tasks that you can perform through the Billing & Subscription page in QBO. You can upgrade or downgrade your subscription, and view your payment history. To learn more about this, kindly visit this article: Update your billing and subscription info in QuickBooks Online.

Please know that you're always welcome to comment below if you have other concerns or follow-up inquiries about managing your QBO account. I'm just around to help. Take care always.