Via the AppLovin dashboard you have the ability to set defaults for the ad format settings of new/existing applications. In the AppLovin dashboard:
Monetize > Manage Apps > Manage Defaults (top right) > Select Platform > Select Default Settings > Scroll down and click "Save"
If you wish to apply these defaults to your existing apps, select the box at the bottom of the page labeled "Also apply these settings to all your existing [Platform] apps."
See our Manage Apps tutorial video for more info on configuring app settings in the AppLovin dashboard.