EtchRock will recommend challenges to you based on your interests. To update your interests please follow the below steps.
Using the side menu bar, click on the top icon to open the menu
Click on the profile button and then 'edit profile'.
At the top of the page click on the 'My Interests' circle.
You can then either use the search bar to search for interests or click on the "show all" and you will be able to see all interests and select the ones that you take part in.