Which version of Outlook are you using?
Some settings differ with version. If you're not sure, the "About" box (Help -> About) will tell you:
- Version 16 = Outlook 2016
- Version 15 = Outlook 2013
- Version 14 = Outlook 2010
- Version 12 = Outlook 2007
- Version 11 = Outlook 2003
There never was a version "13" for some reason... :-)