Use automatic refresh for Banner ads

An ad unit’s automatic refresh rate determines how often a new ad request is generated for that ad unit.

We recommend using the Google optimized automatic refresh rate. The optimized rate is calculated using AdMob historical data to ensure the ads shown in your ad units are being refreshed at the best rate for banner ads.

You may also set a custom refresh rate of 30-150 seconds or disable refresh rate completely.

1. Sign in to your AdMob account at https://admob.google.com.
2. Click Apps in the sidebar.
3. Select the name of the app associated with the ad unit you want to review. Note: If you can't find it in the list of recent apps, click View all apps and click the name of the app.
4. Click Ad units in the sidebar.
5. Click the name of the banner ad unit.
6. Click  Advanced settings.
7. Click  beside Automatic refresh.  
8. Make the desired adjustments to the refresh rate for this ad unit.
9. Click Save.