The administration mobile app for Office 365 has been updated (or will be within the next few weeks for iOS)
This new version provides a new UI, simpler to use, plus new functionalities like resetting password (if you are not using ADFS or if you are using AADConnect with Password synch and password write-back), having the same admin features as with the new Office 365 admin portal.
If you already have installed the app, this should have been automatically updated (depending of your App Store configuration) or go there to get it https://aka.ms/office365adminapp