Beware of calling
Settings.Default.Reload();
after each
Settings.Default.Save();
Save() function actually saves your changes to the file but it is not reflected to your running code. Thus, your code keeps the copy of the previous version of the file.
When you call Save() at another location in your code, it writes over your first change, effectively reverting your first change back to original value.
Very hard to pin down even when debugging.
