Hello Kees Kievit ,
Thanks for reaching out in the Microsoft Q&A!
Switching accounts within the Microsoft Authenticator app isn't directly supported, but you can manage multiple accounts by following these methods: first, you can add a new account by opening the app, tapping the "+" sign, selecting the account type, and following the setup instructions. Alternatively, you can remove an old account by holding it and selecting "Remove account" before adding the new one. Once added, you can switch between accounts within the app, as it will display all connected accounts when you need to approve a login. For further guidance, refer to the Microsoft documentation on Microsoft Authenticator and a general overview on setting up multiple accounts. If you find this helpful, please accept this answer to close the thread. Thanks!