Dale there are actually three methods of changing steps in your firmware are three ways' of accessing steps per mm.
1) get a copy of the firmware open it with an IDE make the desired changed then compile and load to printer. I believe this is the method carl refers to.
2) access the setting though control software.
In repiter Host under config there is a option to read and adjust these settings under the option Firmware eprom settings.
The chitcat option needs to be turned on in the firmware for this to work .
I expect other host programs have this option as well.
3) last but not least you can use m codes to read and adjust these settings.
There are several tutorials on line that explain the procedure
https://all3dp.com/2/how-to-calibrate-a … explained/
M503 lists current settings
M92 enters a new value ex M92 X98.52
and m500 saves the new value. you will have to calculate the new value for each axis.
Probably a good idea to calibrate your extruder first then the x,y.z
hope this helps
Soliddoodle 4 stock w glass bed------Folger Tech Prusa 2020 upgraded to and titan /aero extruder mirror bed
FT5 with titan/ E3D Aero------MP mini select w glass bed
MP Utimate maker pro-W bondtech extruder
Marlin/Repetier Host/ Slic3r and Cura