Summary There is no single place to change location and other information about yourself but here are the common ones.
Your web page and Department web page
this should be straight forward, you can change your location data on your own web page and my be able to do the same for your Department page this will vary form Department to Department. For example for Science IT go to https://www.sit.auckland.ac.nz/People and login, select edit details in your staff entry and change the building to 312 and room number 398 and click save when you have finished changing your details.
Go to https://iam.auckland.ac.nz and login, go to your identity details, select the address tab and click the update tab for Campus Address and change the location details to include Building 312 room 398, save the changes.
Open https://staff.auckland.ac.nz and login.Put your name into the search field on the top right hand side, click view profile, view full profile, and edit profile (top right hand side), edit the Primary Location, enter the building number 312 into the location search, select it and then choose the floor 3 and room 398. Click save to save the changes, and done editing to finish.