Hello  @asnyder11 ...

In classic Quizzes, the only way to change the total points of your quiz is to modify the number of points for each question.  Once you modify the points for each question, the overall total of the quiz will be updated.  There is no way to just modify a "Total Points" field in classic Quizzes because it is adding up the total of all points for all your questions in the quiz.

In New Quizzes, you should be able to create a set of question (let's say 28 questions at 1 point each).  Then, you can modify the assignment (quiz) details to increase the total score to 40 points...keeping each of your 28 questions at 1 point each.

If you do not have New Quizzes available to you at your school, you will need to talk with your school's local Canvas administrator or someone in your school's Online Learning/eLearning department to see if they have enabled it yet.  Some schools have not done so, and your school might be waiting a bit longer to enable New Quizzes for you and your colleagues.

I hope this will help, Angela.  Please let Community members know if you have any other questions.  Thanks.  Stay safe...be well.