Removing Account from Outlook app for Android mobile phone or tablet Please verify you are running the most up to date version of the Outlook app.

We have verified this behavior on multiple different Android devices in testing, so we recommend you remove the old account completely. This appears to be a flaw in the Android app and has been reported to Microsoft. When being migrated to Microsoft 365 If you are currently using Outlook app on your Android mobile phone or tablet to access your Exchange mailbox, you will need to remove your old account information from the settings, and re-add your account as new, otherwise you may end up with both new and old account information in the settings on your device, and constant password prompts to log in.