You can choose to receive verification codes in the Google Authenticator app.

To activate Google Authenticator

1. Click Enable in the Google Authenticator section of Settings → Security → Authentication Methods.

   
   
    

2. Choose your type of smartphone. Click the image and follow the instructions to install the Google Authenticator mobile app.

    
   

   
   

3. Tap Scan Barcode in the application. Scan the QR code displayed on the Account Security page. If you failed to scan the QR code, a new code will be generated. 

   If you cannot scan the QR code, click Having troubles scanning code, and then enter the key manually.
   

4. The Google Authenticator app will start generating security codes. Security codes are time-based and change with time.

   Enter the code generated in the app and click Enable.
   

To successfully use Google Authenticator (GA), the time on the device running the app must be correct.  Normally GA relies upon the device time to generate security codes. The Android version provides the TimeSync feature to solve the problem when the time on the device is significantly inaccurate.  To get valid codes, set the date and time on your device correctly.

To deactivate Google Authenticator

1. Click Disable in the Google Authenticator section of Settings → Security → Authentication Methods.

2. Enter the one-time code generated in the app, and then click Verify.