I go to properties and change the font and buffer size, and when I press okay, I get:
Unable to modify the shortcut.
I checked to make sure it has not been deleted or renamed.
I've hit the same sort of problem before, and it's mainly because my user account does not have the right access to update the profile. Try launching the PowerShell console elevated (i.e. right click the PowerShell shortcut in the Start Menu, and click "Run as administrator"), make the changes to the console properties, and close the elevated console. The settings should stick when you next run PowerShell as you normally do.
Go to Start -> Windows PowerShell, right-click on the icon and choose Copy.
Open the Start -> Programs as a folder and paste the shortcut you just copied. Rename it, say MyPowerShell.
You should be able to modify the settings of this shortcut. Use this shortcut to launch PowerShell.