Select an audio recording format that takes quality and memory usage into account. 8 bit resolution on 12 kHz sampling is low fidelity (but OK if you just want to tell the difference between a car and a dog). It is of course nice to have "full CD quality" on all your recordings, but it will use a lot of the memory in the instrument. (Up to 16 times more, and memory is running fast.)
48 kHz sampling rate is ideal for quality recordings. Use this selection if the recording shall be analysed later.

The Nor150 measures the whole dynamic range in one span without any gain adjustment. The full scale with a normal microphone is 140 dB. If the level is low, like speech, adding a gain (e.g. 24 dB) will make it much easier to use the recording in a playback situation later.
Please note that adding gain to your recording implies that there can be unrecoverable overloads in the file and that background noise will be more audible. In fact the dynamic range will be reduced with the gain setting.