This is usually a problem caused by a miss-match of the OS language and Keyboard language. We don't have many Mac users on this site. So I don't expect you to get a Mac specific solution.
I found this solution on Kioskea:
If you are on a Mac, this is what you do:
Click on the apple in the upper left corner of your screen.
Select System Preferences
Click on Input Menu
Then select the language you want, ie: American English or whatever.
That should do the trick!