The details panel is found at the right hand side of the Search Editor.
Two Keywords filters.
Depending on what tab is being viewed (Input or Output), the Details panel will have different controls. The Details panel's controls in the Input tab will also vary according to the selected Draft - Comparison Type and whether a filter is a Meta data field or Table and column element, eg a free text filter cannot have Predetermined values, therefore there is no "Add predetermined value(s)" button; and a Table and column element cannot have a Draft - Field applied to it, therefore there is no "Add field" button for such an element.
The details panel is used to view more finely grained information and to edit a filter or value field. Anything except the data, which an element works with, can be edited in the Details panel.