thermometer/hydrometer and incubator temp confusion..

[remicuties]

So I recently bought a hovabator 3270 and an incutherm pro therm/hydrometer and doing all the research before I start hatching as I’ll be doing emu eggs and want the most accurate readings possible..
I saw the salt test with hydrometers, still confused..
What reading am I supposed to be using when checking humidity and temp of my bator? The incubators readings… or the thermometers?
Also do both the incubator and thermometer need to be calibrated to read the same..?

I saw a video on recalibrating the temperature of the specific incubator I got and it made me even more confused.

Let’s say I salt test this incutherm and it reads a degree above 75% (given no matter what the salt test is 75%) do I just add a 1 to every reading I do with the thermometer in my incubator? Or Is there a little button I can press to recalibrate?
But again.. what purpose does an incubators temperature reading have if all I am doing is using another thermometer to get what the temp and humidity is inside it?

Someone enlighten me on what to do as I wanna get these things calibrated when they come in so I can have the most successful hatch possible