I'm not sure I understand your question properly, but if you select your layer and go to Edit/transform/Scale, you should be able to resize all that's on that layer.  You'll see those little "markers" (not sure what they're called in english, I'm attaching a pic to show you), just put your cursor over one of the corners, hold shift and drag that little marker to resize the way you want it.

Lucie
finfond.net
finfond.net (store)