If you want to add customizations for an individual student, click on the three dots to the right of the student’s name and select customizations.
These customizations will then only apply to this specific student and will not affect the other students who write the test.
For customizations, you can choose the background color of the writing surface. Some students with dyslexia, for example, prefer to have a pastel background. Talk to your students and ask what that particular student prefers.