How to change latitude numbers?

I set a default location, and I want to play with the latitude numbers. The problem is, after I set for example, Latitude N 90° 00' 00", and pressed "ENTER", nothing happens. It keeps going back to the default city, and I cant take the "check mark" off the default box.

So the question is, is there any way I can change the latitude numbers?????

PS: I tried on both my iMAC and Win7 64bit, same problem occurred.