With such a variety of Cardboard devices and variations in lens distance, field of view, distortion, and so on, Cardboard apps must be configured to a specific device's attributes. Google provides a solution to this as well. Each Cardboard viewer comes with a unique QR code and/or NFC chip which you scan to configure the software for that device. If you're interested in calibrating your own device or customizing your parameters, check out the profile generator tools at https://www.google.com/get/cardboard/viewerprofilegenerator/.

To configure your phone to a specific Cardboard viewer, open the standard Google Cardboard app, and select the Settings icon in the bottom center section of the screen, as shown in the following image:

Then point the camera at the QR code for your particular Cardboard viewer:

Your phone is now configured for the specific Cardboard viewer parameters.