To update the posting preferences for a challenge in The Conqueror app you need to following these steps:
Login into The Conqueror App.
In the main screen, refer to the lower pane and select the last icon to the right as shown below.
From the options, select "Posting Preferences".
Once in the Posting Preferences section, you will find the list of your challenges. Find the challenge that you want to update and click on "Update Your Posting Preferences" as shown below.
The posting preferences should be revealed for that specific challenge. You can tick on the sources and activities types that you wish your challenge should accept and then you click on Save (see below):