RECORDING WITH PSR SX700

[DIANADIANA]

I'm using audacity software. I has audacity with my old psr 3000. Recently i have connected the psr sx700 as the same mode of my old keyboard. One cable to pc. When i'm try to record audio signal, the audio signal is very low. I don't know. On audacity i can set stereo mix device, but i can't register audio signal, with these setting. I can use only "mic hight definition audio device". With microphon i can register the audio signal from my keyboard, but is very low. With my old keyboard, i have using he same method, and the audio signal was not so low.
I'm search the best method and setting, for registered one good audio on pc, only with my keyboard and microphone on my keyboard, as old time

wich cable i can use. i have one audio cable into my keyboard, inside "main output l/r". I don't use another cables at the moment