Map scale doesn't change in map editor?

[basicbh1]

I've been working on a standalone project and the map scale wont change when I change the numbers. Go to tools>settings and then change the scale from 1:19 to 1:1 or any other scale number and it doesn't change. I save it and it reverts back to 1:19 scale.

Any reason why its doing this? Any help would be appreciated, thanks.