Microphone extremely quiet

For some time, my microphone is extremely quiet when doing things like making voice messages on WhatsApp or when calling someone. I searched the internet for a solution, but I couldn't find anything except for some apps which didn't work (or only worked in the app itself but outside did nothing). Is there a config file with the microphone volume so I can adjust it myself or some script or so? Wired headset microphone is also extremely quiet. ---------- Information that could be relevant to this problem: Samsung G900f (S5) Android 6.0.1 / Cyanogenmod 13 Baseband version G900FXXU1BOD3