Yes, you can!
Once the testpaper is generated and saved as a draft, the questions can be deleted or replaced. Once done editing, you can click on finish editing.
In the case of a normal testpaper, you can simply save them as a pdf or copy the questions on the testpaper and use word processors to edit them to your liking.
You can add your school name, logo, and other information as well as also change the questions.