How I set default sound card

I have 2 sound cards : one is on board and other is Creative sound blaster.
I want to play sounds just on Crative.
The problem is when I reboot the PC the sound is change,sometime the default sound card is Creative sometime is the onboard card.
I want my default sound card to be only Creative.
How to do that?
Thank you

In Yast Hardware Sound

Configure Creative as: sound card 0

Adding to carl’s post

YaST > Hardware > Sound, select the card, click the button lower right and select: Make this the default.