HMC5883L and MicroMag3 help

Hi guys, I am a bit new at all this stuff but I have a lot of enthusiasm about electronics. Happy to be a part of this community! I am playing with HMC5883L breakout and MicroMag3 magnetometers and I have some issues determining the measurement units of those sensors. The goal is to reach maximum resolution on both sensors (500 nT for the Honeywell and 15nT for the PNI) and the deliver output values in nT (or anything convertable to nT units). What are the default units (if any..) and how to set up gain and etc. to retrieve data in maximum resolution and proper units?
Thanks in advance guys, so far this forum has been my guardian angel in electronics, I really hope you can help me about this one!

Alright, I thing I made a progress with the HMC5883L. As far as I understood the examples and the datasheet, the output units of the scaled values is mG, which multiplied by 100 converts the units to nT.

However, the MicroMag3 is still a mystery for me... anyone?