When I’m creating an invoice the app on my phone is automatically adding a random payment resulting in the total amount owned on the invoice to be wrong!

Glad you're here in the Community, @matthewturner199. I'm here to help fix the issue with your invoices in QuickBooks Online.

It's possible that your QuickBooks Online (QBO) Mobile app had a data issue that's why it's added a random payment. To get this fixed, let's refresh your mobile app data from your phone settings.

The steps to do this may differ depending on the OS you're using.

For Android, here's how:

1. From the More Options ⋮, select Settings.
2. Tick Refresh Data, then choose Yes.

For IOS:

1. From the Menu ☰, select Help & Feedback. 
2. Click Refresh Data, and then select Refresh.

You can also do it in your device settings. Here's how:

For Android:

1. Go to your device's Settings, select Apps (varies by device).
2. Choose QuickBooks app from the list, and then pick Storage.
3. Finally, hit clear data.

For IOS:

1. Go to your device's Settings, select Setting General iPhone Storage.
2. Choose an app that's taking up a lot of space.
3. To free up the storage without deleting the documents and data for the app, select the Offload App.

Once done, try to create invoice(s) again to double-check.

If the issue persists, you can try uninstalling and reinstalling the app to refresh the connection between your app and mobile. You can also open your account through a web browser.

Also, for the payment that was added, you can manually delete them. For more details on how to delete them, see this article: Delete an invoice payment using the QuickBooks Online mobile app.

I've also attached an article you can use to enter a payment using the QuickBooks mobile app: Receive an invoice payment using the QuickBooks Online app.

If you have other questions about QuickBooks, just let us know by adding a new post below. We'll be around to assist you as soon as possible.