Hi IanB3, thanks for posting on the Community
We're sorry that your post wasn't picked up at the time of posting. If you still need guidance on this, please follow the advice below.
To ensure your MTD credentials are correct, disconnect and reconnect MTD in QuickBooks. To do this, access your MTD settings:
1. Select the gear icon, and then Account and settings.
2. Select Advanced.
3. Next to Making Tax Digital, select the pencil icon.
Disconnect from MTD:
1. In Advanced, select Making Tax Digital to expand the section.
2. Select Learn how to disconnect.
3. Select Continue.
4. Select Disconnect to confirm.
5. Select Continue to return to QuickBooks Online.
Re-authorise MTD:
1. Go to Taxes and select Set up MTD.
2. Select Authorise now.
3. Select Continue.
4. In the window that opens, sign in with your MTD Government Gateway user ID and password. This will be in the confirmation email you receive from HMRC.
5. Select Continue.
6. Select Give permission.
7. Once you're connected, select Continue and then Go to Taxes.