Noobie Maintenance Question about changing fluids
 

I am confused about what I should change on my 2012 GLK 350 4matic

specifically I am confused about these terms:

transfer case
transmission
torque converter
front differential
rear differential

and how often should these be changed?

There is a free App, Mercedes Me, that has a manual

Transfer case is part of transmission. Transmission fluid is every 40k miles.
Transmission - see above.
Torque converter uses the same fluid as transmission and holds 3-4 qrts. When changing transmission fluid, you can also drain the torque converter to get more of the old fluid out. There is no specified interval as it's the same fluid is part of the transmission service.
Front differential - no interval from MB, but every 90-100k miles seems to be the norm (I would do it every other transmission flush). Front differential doesn't have fill plug. You drain and fill through the same drain hole. Good thing is the adapter that screws into transmission to fill it also works for the front diff, so you pump whatever came out plus little extra to account for spillage.
Rear diff - the same 90-100k mile interval (not specified by Mercedes). There is a fill and drain plug, so nice and easy.

Thank you for taking the time to answer my questions. Big help!