For EditForm:
In Custom JS add this
jQuery(“#dffs_Dropdown select”,”dffs_Dropdown2 select”).css(‘background-color’,’#ffcccc’);
For DispForm:
In Custom JS add this
jQuery(“#dffs_Dropdown td.ms-formbody”,”dffs_Dropdown2 td.ms-formbody”).css(‘background-color’,’#ffcccc’);
In DispForm it highlights the entire cell so you may want do change it to just ‘color’ and you’ll just change the color of the text.