Have you ever correctly set the audio sources? Actually, I have used OBS before and it's indeed reputable in the recording. However, I found it much hard for me to operate as I don't have enough skills. Recently, I got a similar screen recorder called Joyoshare VidiKit (originally Joyoshare Screen Recorder, maybe you have ever heard) from giveaway, which works as screen recorder, audio capture, video cutter, video editor and more to post-process files. I can easily record audio from my computer system itself and the microphone in high quality!