On old FMC -
- Init A + B inaccessible. Use FUEL PRED page.
- Also if you need to change the ALTN you have to do the proc
as per FCOM.
On new FMC -
- Init A + B accessible. Means also you can change the ALTN
directly on Init A without going through all that rigmarole of
the old FMC.
BTW lad don't jump ahead too much before the CBT or you'll
attend it in utter confusion. Any reasonably good course will
have an instructor hanging around to answer such questions.