In previous versions there was a way to set the window configuration as default. But now in Yosemite they seem to have got rid of this option.
There is however a way to make it remember for a while with
option + drag a new (untouched) finder window. But this won't last long. After a while or a restart the window is back to stock settings.
Is this a bug? Because I can't recall experiencing this in previous versions of OS X. If not, is there a way to set a default window configuration?