I doubt if your password in Outlook was wrong. This is a common issue in Outlook 2016. I have multiple passwords saved in Outlook for various accounts that have been unchanged for many years. Outlook 2016 constantly prompts me for my various passwords all day long every day. I just press the button to re-save them and it works fine until the next time it pops up and I have to do it again. This is another one of Outlook 2016 many design flaws. I've had to do it hundreds of times since installing Office 2016.