Any time anything is posted into News Feed or Crowd Pics type pages in an app, a user could get a notification. How frequently they get notifications and from whom depends on the default notification setting set by the app's creator.
If you'd like to change those settings to receive fewer or more notifications, you can do that in the Yapp app.
Find the app you'd like to adjust notification settings for and long-hold down on it. A box will pop up with "Share", "Notification Settings" and "Delete" options.
Within the app that you'd like to adjust the settings on, tap the icon in the upper left corner to open the pages drawer. "Notification Settings" will be at the bottom of the list.
When you click on "Notification Settings," you'll see 3 options:
All Activity: this alerts you any time anything is posted into News Feed or Crowd Pics).
Creator's Notifications: this only alerts you when the creator of the app posts into News Feed or Crowd Pics, or when they broadcast a post.
None: this turns off all alerts; you will not receive any notification when someone posts into News Feed or Crowd Pics, or when a creator broadcasts a post.
Choose one and tap 'OK' to save your notification settings.
Please note, you will need to have accepted notifications from Yapp from your OS (iOS or Android) to receive any notifications from any of your apps in Yapp.