Your primary contact address is where you will receive your Peerio notifications (if enabled) and important updates from Peerio.
To change your primary contact address, go to your profile by tapping the menu button at the top left of the app then tapping "Profile":
Once in your profile tap the address you would like to set as your new primary address.
The green circle indicates which address is set as primary.
To change your primary contact address, hover over your name in the bottom left-hand corner of the Peerio window and click "Account"
Under "Addresses", click the star next to the address you would like to set as your new primary address.