If your phone number has changed, you’re going to want to update it on Instagram so you can always access your account properly. You can do this by accessing your personal information from your profile settings and/or your security settings from your account settings.
How to Change Your Phone Number on Instagram for Logging In
Follow these steps to change your phone number in your personal information settings so you can use it to log into your account. You can do this from the mobile app for iOS/Android as well as from Instagram.com on the web.
How to Change Your Phone Number on Instagram for Two-Factor Authentication
Although you can disable and enable two-factor authentication both from the mobile app and from the web, you can only change your phone number used for two-factor authentication via the mobile app. If you change it, it will automatically update the phone number you have in your personal information (used for logging in).
