Bonjour Elizabeth,
With Kwiziq writing challenges, once you have submitted an answer, you cannot go back over it. Unfortunately, this isn't a feature that is available at the moment. Once the writing challenge is completed, you can choose to do the exercise again by clicking on 'Or, try this Exercise again'.
The link below will take you to an explanation on how the writing challenges work: faq/writing-challenges
I hope this is helpful.
Bonne journée !
