@Kalle
Thanks for reply.
Audio "setting" can be changed in sonar performance page.
I just have been change sample rate between 44100 and 96000(or 48000) by changing value in performance --> audio --> driver setting --> sample rate.
I barely remember(or it's wrong) that Sonar X1 could save sample rate per project by default. So when I try to open some old project, it is 44/24 altough others are opened with 96/24. But when I was using X1, I couldn't change sample rate of the project after project is started (I could choose sample rate only at the start of the project or I had to create new one) while it's possible in X2.
So I wonder if audio sample rate and bit rate can be saved per project like X1.