no sound

HI can someone please help.Im using sonar 8.5 and everytime i open a project there is no sound even though i can see all the meters working.Only when I right click on the master track and select "set all bus outputs" and choose my soundcard output does the sound work.i have saved after doing so but still the problem exists as soon as i open  another project.btw i am using two delta 1010 cards.