There is time for humility and humbleness, and there is time for poise and confidence
Ideally, one is always poised and commanding as befits one's position/status. If one can manage to be that, s/he has no difficulty to:
1) Be assertive, but not arrogant;
2) Be confident, but not boastful;
3) Be self-assured, but not self-righteous; and
4) Be humble and modest, but not timid or self-doubting.
Failing the above, one can always reliably fall back on this ageless wisdom: There is time for humility and humbleness, and there is time for pride and confidence. Take your pick and make the most of either setting.