5.6 Upgrade - Page Defaults
PermalinkDefaults
Settings
Composer
Maybe they are being cut off by your browser window?
The system only shows two admin users, and the other admin user sees the same thing I do, as well as when I'm signed in as the main admin, I can "sign in as user" which I thought was a super-user feature.
Are you looking in Dashboard/Page Types?
You should see the Defaults button next to each page type.
What do you see when you get to that section?