You can edit an existing test via the "TEACHER" environment. When you are here, click on the "TESTS" tab. You can select the correct class using a drop-down menu in the top-right of the screen.
Editing a test
You will see a table of all your tests. You can edit your exam in three ways.
You can click on the name of your exam to edit your exam.
The rightmost column has a few icons you can click on. Click on the pencil icon to edit your exam.
You can find your exam on the home screen. On the bottom-right, you will find a list of the exams you have created and made available to students. You will find the same pencil icon there as well. Click on the pencil icon to edit your exam.