You might also like:
Later this week, United will be changing the process for logging into your MileagePlus account. While the carrier had already begun requiring passwords to sign in online since February 11, as of this week, you won’t be able to use a PIN to authenticate your account over the phone either. The airline will also employ two-factor authentication in order to better protect your frequent flyer account.
If you call United after the changes go into effect, you’ll soon be asked for the password you use to access your online account if you interact with the automated telephone system. If you speak to a customer service representative, you’ll also be asked to provide answers to your security questions. Additionally, when you sign in to your MileagePlus account on a new device, the system will prompt you to answer your security questions. Don’t worry — if you’ve already forgotten the answers, you can still sign in to your account and select different questions and answers.
Source: thepointsguy.com