Thanks for the help
if you AUTO BATTLE, you will find that the unit size DOES work, as your units will 'decrease' if some are killed, but the value 'sticks'.
i cannot modify the hard coded 'unit sizes' in battle that is played out fully in battle mode. having 10000 archers moving in a single formation would be stupid, and further would likely crash your computer. they imposed a limit on this and it's hard coded.
the increased troops is for auto healing your group and/or using in auto battles.