Select branch by default

Question

It's a school form page where branch Id is in drop down menu.
Tell me in details I'm stater.
Remove branch drop-down from every form and make an hidden input field and echo the value $_SESSION['branch_id'] to that hidden field having same name attribute value as that of Dropdown.

Answer 1

"Remove branch dropdown from every form and make a hidden input field and echo the value $_SESSION['branch_id'] to that hidden field having same name attribute value as that of dropdown."

I'm sorry, but I don't understand how can the hidden input value be the same as that of the dropdown when you said you wanted to remove the branch dropdown from every form?