If you choose to configure a screen you will see, that each field now has an ID as text. This will make it easier for you to locate your field.
System fields provide IDs. Custom fields provide IDs.
Screen schemes also have an ID. They can be filtered by name or issue type screen scheme. (See the table above).
Issue type screen schemes can be filtered by name or project. They also provide a searchable ID. (See the table above).