Device or resource busy after using micArray example

Hello , here is the issue , I had micarray example working good , I wanted to use matrix audio input as default i followed this steps , it works good but there is a problem once I execute the micarray example (c++ code that records a raw file) and then I launch arecord recording.wav -f S16_LE -r 16000 -d 5 it tells me rec FAIL formats : can’t open input ‘default’ : snd_pcm_open error device or resource is busy , Also I need the default input to be with beamforming since I’ve noticed that there is a different in sound quality between (c++ code which uses beamforming) and arecord command which uses only one mic as input , thank you so much.