Changing part names

I'm using 4.2 version. I created a piece with six parts, naming them in the score, Clt 1, 2, 3, 4, 5 & Bass. Later I deleted Clt 2 and re-named the other parts accordingly, still in the score. But when I go to "export a PDF" to print each part separately, in the export dialogue box the re-named parts still have their old names, which end up on the printed copy. Where should I have changed the names? I've looked everywhere.