Select deck 1/3 and 2/4 with the shift button. I suggest you switch to shift lock (on the back on the beat pad)

All normal "shift" functions are available by pressing "REC"

You can now control all functions as normal.

Here are some additional functions you will find. 

Central controls. 
- Trax will scroll and toggle library 
- REC + Trax press will preview the selected library track in your headphones 
- REC + track load will load the track (sorry but shift plus load fires the auto line fade) 
- PFL button will automatically precue the track in your headphones (try it) 

Equaliser 
- REC + pitch, line fade, gain, and lo, mid, high give you instant access to the opposite deck for quick adjustments. 

Instant FX 
- REC + Pads gives you additional effects 

Bounce 
- REC + Pads gives you additional bounce lengths 

Sample 
- REC + Sample stops the current sample 

FX 
- REC + FX, Parameter gives acces to FX 2 on each deck 

Loop 
- REC + Loop allows you to skip the loop