There are several ways to get to the Author environment for exercises:
In the Author environment, click on the Exercises tab. Select an exercise by clicking on its name, or by clicking on the pencil icon to its right. If the pencil is not available, you probably don't have edit rights in the Author group. You can always use the search bar to search for exercises by name or by ID number.
2. Is the exercise you want to select already available in one of your classes? Find the exercise you want to edit on the homepage (which shows your current course).
Open the package and navigate to the right exercise. Click on the pencil icon to the right of the ID number.
NOTE: You will see two pencil icons; the one on the left allows you to edit the package instead.
3. You can also open the exercise in edit mode via the right-click menu of the item in the Edit chapter or Edit subchapter page.
4. Finally, you can also access Edit exercise by clicking on its name in the Edit package page.
Editing an existing exercise
You will now see a top menu similar to:
This means you can start editing the exercise. For more information about what you can do while editing an exercise, see this page on creating a new exercise.
Be aware, if you want to make major changes in an exercise that is already being used in active classes it might be smart to make a copy first and continue editing this copy. Don't forget to add the copy to the package you want it to be in. This especially holds for exercises that are being used in tests and exams already.