Hello Martin1977, thanks for joining the Community
To reset your HMRC credentials in QuickBooks Online, begin by turning MTD off by following the steps below:
1. Select the gear icon and select Account and settings.
2. Select Advanced.
3. Select the pencil icon next to Making Tax Digital.
4. Select Learn how to Disconnect and follow the steps.
After this, log out and back into QuickBooks, then navigate back to the MTD settings and select 'Learn how to connect'.
