Many have asked so I'll just answer here.

There are 4 fills and 4 breaks (although the panel only shows access to 1). Depending on which Arranger you are in (e.g. if you are currently playing ARRANGER B), if you press the dedicated FILL or BREAK button on the panel, you will get FILL2/BREAK2.

However, if you choose the ARRANGER screen (as shown below), you can have access to the dedicated FILL INS/BREAKS and press any right there on the touch screen - regardless of which ARRANGER you are in ...

Hope this explanation helps.