Sounding during playback even though unchecked it can still be heard in background.

Welcome pianopicr

Usually this happens because of bleed, ie. the mic picking up the sound of the monitor or even the headphones if they are loud enough and the mic sensitive enough. It really depends on what you're using, and what you're recording. A couple things you can do, make sure to use headphones, the more isolated the better. Also iOS has a bunch of processing on the internal mic and headset mic, and it includes a compressor which can make the background noise much louder. To turn this off, go to the Settings app -> MultiTrack -> Measurement Mode -> ON. The recording level will be reduced, but the iOS eq and compressors will be removed from the input.