You can make changes while you're completing the questionnaire. Instructions on how to go back in the questionnaire without having to start over are available here.
Once you submit your questionnaire, you can't return to it to. Instead, you can use the case editor in your my.upsolve account to correct your mistake and update or add information as needed.
To access the case editor click “Update Info” button at the bottom of your my.upsolve account. The case editor is only available after the questionnaire is completed.