You can filter stories by topics via a top filter All Topics. If you have previously selected a country for trending stories, the drop-down for topics will only show topics which have stories in this country.

To choose a topic:-

For Android:

1- Tap on Search from Task menu 

2- You will find the Featured Topics and stories as below:

For iOS:

1- Tap on Search from Task menu

2- You will find the Featured Topics and stories as below: