Website:
- Sign in and tap 'Achieve'
- Visit the Challenges page
- Click on the challenge of interest
- Information on challenge history is available in the 'History' tile
iOS and Android Mobile app:
- Sign in and tap the 'Achieve' icon at the bottom of the page
- Tap 'Challenges'
- Click on the challenge of interest
- Scroll down to the tile where you will see the 'History'