Editing a Search Form which is a symbol

I have a search form (to search available homes) and I want to add in another drop-down field, so a user can search by “Completion date”. I can’t seem to get it to work. PLEASE HELP!


Here is my site Read-Only: LINK

https://preview.webflow.com/preview/berkeley-building-co?utm_medium=preview_link&utm_source=designer&utm_content=berkeley-building-co&preview=ba59bbe73f9513243d389e37a998b51f&pageId=60f6f764001cbb379ff5c664&workflow=preview
(how to share your site Read-Only link)