Hello Robertwebb, thanks for posting on this thread, if you disconnect mtd fully from the account and settings and then reconnect it up again using the correct details. 

1. Click the gear icon and select Account and settings. 
2. In Advanced, select Making Tax Digital. 
3. Hit Learn how to disconnect and follow the steps. 

Once you have disconnected, let's get you reconnected. 

1. In the Advanced section under Account and settings, select Learn how to connect.
2.  Select Let's go, this will take you to the HMRC page. Once you have read the guidelines, select Continue. 
3. Enter your HMRC credentials to sign in. 
4. Select Grant Authority and the HMRC page will close. 
5. Back in QuickBooks, select Continue. 
6. Go to Taxes, and check that the MTD badge is enabled.

All done! You're now reconnected and can submit your VAT return for MTD through QuickBooks.