The polls that you are seeing on your profile are taken on a separate survey than the initial review survey. Currently, this second survey is a little hard to access, which our Product Team is aware of - we are in the early stages of working on an update that will make this survey easier and more intuitive to access.
Users are able to fill out this second form after the initial review process by clicking the "review my school" button on a school they have already left a review for. This form will present various poll questions, such as "What are your favorite school events or traditions?", or ask students to rate how they feel about their school on various topics, such as safety, teachers, and clubs. These responses populate the polls across the school's profile. The questions on this survey are not required in order to submit the survey, which is why you might see more responses on one poll on your profile than another. We require at least 5 responses to any individual question before we will list results on a profile.
We would recommend asking your students who have already left reviews on your school page to log in to the same account they used to leave the initial review, and click "review my school" again, where they will be able to fill out these polls.