A please.
The full score has two parts on the same staff. The players parts are printed with each part on a separate stave, but both on the same sheet.
Of course, the answer is simple once you find it. There is a check box in the Staff Properties dialog: "Staff name in parts"
The printed page. The only solution I've come up with is to create a new staff with cello in layer 1 and bass in layer 2 and hide the originals. But if I make a change or correction, I'd have to do...