Hi,
There is a known issue "Outlook and other apps won't remember password" after instaling Windows 10 Version 2004 Build 19041.173 and related updates.
Please check below articles and try the workaround.
https://support.microsoft.com/en-us/office/outlook-and-other-apps-won-t-remember-password-after-windows-updates-1e5a8a80-7112-440a-a18c-be2e50047a75
https://answers.microsoft.com/en-us/windows/forum/windows_10-update/outlook-not-saving-passwords-after-windows-10/23b8609c-ccc0-4cfe-9b0b-20fca17cf088
Or maybe you can try to update the windows to the latest version (20H2) and see if the problem could be resolved.
Thanks,
Eleven
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