thank you i was using pd extended and asio4all was not working , now it works !

Hi everyone !
I am a pd new user and I'm trying to do a 4 channel installation for an school art project
Im using a ´Focusrite scarlett 2i4 as an external device, but when I use dac~ 1 2 3 4 outputs 1 2 goes out from the scarlett and 3 4 from the pc i dont know what´´s happening . Does anybody know how to fix this ? Is there any way to configure the external device other than the main menu audio settings ?
thanks