Admins are by account not app. Therefore, admins have full admin access to ALL the apps on the account.
If you are a consultant you may be an admin on multiple Stacker accounts.
Instead, of signing into each account individually, you can now view and access all of your apps in one place.
How to get there: Click on your initials in the top right corner > Select "My Apps"
For example, a consultant is an admin on both the "Miller Co" and the "Smith Company" account. He can easily view the apps in each account using the Account Dropdown to switch between the two.
The account dropdown (shown below) will only appear if you are an admin on multiple accounts.
If the consultant was to click the "Add new admin" button, it would add an admin only to the account that is selected.
For example, the consultant adds an admin while on Account 22682, then the new admin would have access to all the apps on Account 22682, or the "Miller Co" account.