XDJ-XZ preview cue setting

https://forums.pioneerdj.com/hc/en-us/community/posts/360061632231/comments/360010344431 (Follow up with this ☝️ ) I have issue with preview setting on XDJ-XZ , when I signed the channel 3 and 4 for preview channel it didn't work, can you share you step by step guide for this ? How do I preview song on XDJ-XZ?