I'm on Office 365 desktop and MS seemed to have "simplified" the IMAP account settings: http://www.veryrisky.co.uk/webimages/newoutlooksettings.png so I have no way of updating the passwords if they are changed. Or for that matter doing any of the old advanced setup if the ports were wrong. What is going on, why I try help I see examples using the old dialog and I can't find any reference to this new one.
Fixed, I tried the online help chat and someone pointed me to >Windows Control Panel >Mail (Microsoft Outlook 2016) where the old accounts settings dialog lives! They also gave me a month's office 365 for my trouble which was a pleasant surprise!
