How to format Dropdown Menu with Dates and Times

I am new to Corvid. I followed a video tutorial on how to make a quick book bookings form. I am pretty sure I followed all of the code. My problem: I chose to drop down menus like the video said, and then later put code in. But when I preview the drop down menus have their default choices (e.g., which flavor, etc.). I can go to Manage Choices but that does not allow me to format dates and times. Is there a certain drop down menu I need to select? Code issue?