This page applies equally to both filters and value fields, so for simplicity's sake both of these will be referred to as elements.
Editing an element is done by selecting the desired element in the grid, expanding The Details panel if it is collapsed, change what needs to be changed, click the "Save" button.
Examples
Adding Predetermined values to a filter:
Changing a filter's Draft - Comparison Type:
Changing a value field's isArray property a to a value field: