I have two cameras,one at layer 1,another at layer 2. I´m currently working on a scenario on layer 2,which have some planes with the property halo(to always face the camera).I need the camera on layer 2 to be the new default one,because blender(no matter how hard I try)is always considering the camera at layer 1 as the default,causing the halo plane to always face the wrong camera.
Anyone can help?I´m using the current blender release,I tried ctrl+0 on numpad,but it doesn´t work …
create your new camera , select it and press control, and the numpad 0…
thats it 
right-click (select) the camera, then do view->cameras->set active object as camera. (if the ctrl-0 doesnt do it for ya).
I have done as said.Note that now I passed the scenario in layer 2 to 1,which is where I´m currently working,and yet,I receive a message “no(correct) camera” and the same halo wrong facing problem.
You need to select the layer, then select the camera, then do the CTRL + Numpad 0. You also need to adjust the camera’s view too.
Actually anthing can be a camera by just selecting and doing the above… I have done it by accident and been inside my player wondering where I was, everything was grey. smile.
I did all you have told me,the problem is…no matter what object I set as default(including cameras),the message “no(correct) camera” appears,and halos or billboards don´t work still. I will put the blend below,I hope my project isn´t lost or something.