How should I adjust the buffer size?

By lowering the buffer size setting, the latency (the period from when DDJ-SX2 is operated until the sound is output) can be shortened. If there are interruptions in the sound, increase the buffer size, but note that this makes the latency longer. Set the buffer size to the minimum value at which no interruptions in the sound occur.

For Mac users
The buffer size can be adjusted in SETUP of Serato DJ.

For Windows users
Click the Audio tab in SETUP of Serato DJ and then click the [LAUNCH DRIVER PANEL] button to display the ASIO settings utility screen. On this screen, you can set the buffer size and kernel buffer size.
Set the buffer size to the minimum value at which no interruptions in the sound occur.