Users can manage their profile fields by heading over to their profile>settings cog>edit profile. As an Admin you get to decide what fields are available and what fields are required. A user can change their information at any time but they are not automatically prompted if your team makes any adjustments to required or available profile fields.
If you head over to the Admin, on the left hand navigation scroll down to the section called “Configuration” and hit “Community” this gives you access to the default profile fields and more. I highly recommend creating user groups to gain more control over your profile fields.
Once a user group is enabled you can select which fields are requested, which are required and which should be visible to other users. To create a user group, on the left hand navigation scroll to the section called user configuration>user groups> and hit new user group. These fields can be managed at any time.