Using New Outlook on Windows for professional communication and productivity
Dear JonathanStock,
Thanks for your post in Microsoft Community.
I’ve taken note of your issue. After changing your Google email account, it’s best to reconfigure your account in New Outlook.
Additionally, pay attention to two points: first, delete the previous Google email password credentials from Windows; second, when selecting permissions in the Google account interface, make sure to choose “Select All.”
Please refer to this support article, which provides a detailed description of the above two steps:
Unable to add a Gmail account to classic Outlook - Microsoft Support
Many users have found this operation helpful! I hope it will also assist you!
Best regards
Yolanda - MSFT | Microsoft Community Support Specialist