Every 30 days you will be asked to re-login, this also happens if you use a computer you haven’t used before. You can get codes by SMS or using an Android app (Authenticator or Authy). This section explains how to use Google Authenticator.
First install “Google Authenticator” from Goggle Play/Play Store (this used to be also called the Android Market) on your Android device, or App Store on your iPhone.
Step 1: In Google Play, search for Google Authenticator
Step 2: Click on Install.
Step 3: Go back to your 2-step verification administration panel in your computer browser by going to Your profile picture > My Account > Sign-in & Security > 2-step Verification
Step 4: As you we will be using Google authenticator, click on Switch to app as seen in the next figure.
Figure 15 Switch to Google Authenticator
Step 5: Select the phone type from the options that pops up. In my case, it was Android.
If you are using an iPhone or Blackberry, follow the on-screen instructions for those devices. Click on Continue.
A page will load with a barcode.
Figure 16 (Step 5) Mobile app authentication page
Step 6: Go back to your mobile device and choose Begin setup.
Step 7: Next, press on Scan a barcode.
Google’s or another barcode scanning application will load. If you don’t have a barcode reader already on your device, Google will suggest one and direct you to download it.
Step 8: Use the camera on your device to view the barcode on the computer screen. Google Authenticator will then give you a unique code to type into the box labelled code at the bottom of the barcode page on your computer.
Figure 17 Google Authenticator code from a mobile device
After you click Verify on your computer, you will receive a message to say your Android device is configured.
If you find that it doesn’t work after a few attempts check the time and time-zone is correct on your mobile device.