If you wants to print sub ledger name in credit note without item voucher, you need to design format by adding the sub ledger details for this you need to followthe below steps:
Step 1: Go to Administration, then select Configuration, then select Invoice / Document Printing, then select Advanced,
Step 2: then select the credit note without item , then add the format in credit note without item and cofigure it by loading default format,
Step 3: for further you can follow the invoice design link https://www.youtube.com/watch?v=GABedZfWZOg