I bought LEGO 31313 but I would like to change the firmware for education (45544).
1.09H to 1.09E. Is this possible?
Connect EV3 with USB to computer, have Lego Mindstorm software open
Under Tools -> Select Firmware update and start he update
Brick will restart after firmware is updated
Yes, this is totally possible and I have done it multiple times. You will need access to both firmware files though - AFAIK there is no menu to choose versions.