To personalize the push message icon the Android users of your app will see next to the push message text on the left side, follow these easy steps:

1. prepare your logo with a transparent background (for example, the letter R);
2. open this link: http://romannurik.github.io/AndroidAssetStudio/icons-notification.html#source.type=clipart&source.clipart=account_balance_wallet&source.space.trim=1&source.space.pad=0&name=ic_stat_onesignal_default
3. upload the file on the left side (see image) and then download the image on the right side (see image):

4. provide the downloaded icon to ATOM.

The new and customized push message icon will be included afterwards in your next Android app update.

Note that for Apple the icon is personalized automatically from the start.