Inner layer net definition

Hey guys,
I’m working on a 4 layer board and added the inner layers. I want to set the inner layers as ground and power like the following stack up:

signal
power
ground
signal

I changed the inner layers to power and now I want to use it as power and ground. On previous designs I always draw a zone on the layer and set the net I want on that plane. The question is: Is there a better way to do it?