nux mfx 10

so brought one of these to go with my boss rc 30 looper. the mfx 10 has a 20 second record time which all works fine but if the loop that i record isn't 20 seconds long i have a long pause before it loops again. Is there anyway to change this setting so that when i stop recording it will loop from the start stop point as opposed to it playing silence before looping again ?? on the boss i have to change the factory setting to make this happen. any help would be great as between both my units if i could sort this out it would turn into ... p.s couldn't find any info in the manual as to how you might go about this manual only described how to record a loop many thanks