Yosemite: how to change (main) login display

[Caesar_091]

Hello,

I've recently updated my 2012 Mac Pro to Yosemite.
I've a two display configuration and actually when I turn the Mac on the login windows appears on the secondary monitor and not on the main one (the one in witch once I login I have my menu bar and dock).

Is there a way to change this?

PS: when the screen saver starts of when I wake it up from stop the un-lock screen appears on the right monitor...