Home page is different from other pages and content for home page is controlled with widgets. Navigate to “Appearance” -> “Widgets” page on admin panel. On top right corner you will see “Sidebars” and “Pages” tabs. Click on “Pages” tab and you will see widgets that are displayed on home page. On each widget there “edit” button. Click “edit” on “Ads” widget and set number of ads to 20 or any other amount.
By default there are 2 ads widget one is latest ads other featured ads. You can remove featured ads if you don’t want to use it. Also you can add any other widgets there as well.