If you want to view a specific group member's activity or leaderboard scores, you can filter each by user. Here's how to make it happen:
Step 1: Click to open the Leaderboard or Activity tab.
Step 2: Click the Filter Member dropdown and type the username you're looking for.
Step 3: Click the correct user in the dropdown to filter.
Now that you can filter group leaderboards and activity by a group member, you can easily compare your stats with other group members.