Quiz showing

Each question of my quiz has four possible answers, with only two being correct. For each question, I checked off “Selecting any single correct answer is valid” and “Use checkboxes even if the question only has one correct answer.”

To test, I checked off all of the answers for all of the questions. For 6/10 questions, it marked them as incorrect, which it should. But for 4/10 questions, it marked them as correct, which it should not. I can’t find a reason why this would be happening. Any ideas?

https://www.ads-software.com/plugins/slickquiz/