'Report CSV Separator' in the preferences page will displayed only when the 'Report Excel Export Format' is selected as .csv (Old Excel Versions).

 
Follow the below steps.
 
Log into the Web Timesheet.
On Top right corner click on Settings.
Now on left side pane click on Preferences.
Now select the Report Excel Export Format as .csv (Old Excel Versions).
This will display the Report CSV Separator.
Click on Save.
 
Note: Settings or Preferences will be available in Web Timesheet when administrator provides the proper permission privileges.