Complex sentence: Also, the opening and closing theme of the TV series "The Adventures of Superman" is accredited to Leon Klatzkin, however, Klatzkin was not a composer but a Mutel employee, a film cutter who helped film editors select appropriate tracks for their pictures.
Split into simpler sentences: Also, the opening and closing theme of the TV series "The Adventures of Superman" is accredited to Leon Klatzkin. However, Klatzkin was not a composer but a Mutel employee, a film cutter who helped film editors select appropriate tracks for their pictures.