You can use Roster Update to amend the Shift Code of the Rosters for the period.
Click the Add [+] button will create all Rosters for the given period. The Shift Code of the Roster is default to the most frequency use Shift Code of the Roster.
You can Export the current period Roster information to Excel. Amended and Import back to the system.
The Excel format of the Import file is based on the format of the Export Excel file. See Sample Roster Excel File for Import.