Can't find some sounds

I'm looking for a way to edit this sounds since i couldn't find on Sound Settings

• Start Windows
  
• System Default
  
• Menu Dropdown
  
• Level Lower
  
• Level Higher
  
• Fax Arriving
  
• Netmeeting Leaving
  
• Netmeeting Recive Call
  
• Netmeeting Participant
  
• Reboot
  
• Reboot Navigation