Greetings @regan ,
Thank you for posting on the Instructure Community!
Are you by chance using Classic Quizzes or New Quizzes? With the classic version, you can use the RCE (rich content editor) to access the Greek alphabet. You are able to access these letters by clicking on the equation editor button, then click the 'Greek' tab and you'll have access to the entire Greek alphabet. When it comes to the new version, it doesn't seem that functionality with the Greek alphabet has been added yet. That being said, I'd stick to classic quizzes for now so the Greek alphabet letters work for you!
I hope this helps, always feel free to reach out with any additional questions or concerns!
All the best,
Noah