Here are the steps

Click on "Teacher Schedules" on the left-hand side
Click on a teacher's name
Click on the blue enrollment number on the right-hand side next to the first-period class
You will see the list of students in the class
Click the blue button at the bottom to make the checked students your current selection
Choose the group function "Student Field Value"
In the "field" text box, enter ucf_homeroomteacher
In the "value" text box below it, enter the homeroom teacher last name you want to be displayed on the students' demo page - no spaces or special characters
Click submit
You will get a confirmation of any changes
Click submit again