If a setting does not change how she answers you, it is decoration.
A custom AI girlfriend is only custom if the settings reach the dialogue. Warmth changes how she greets you after a gap. Nerve changes whether she asks the awkward question or lets it sit. Humour changes the shape of her sentences, not just their content.
Appearance works the same way — hair, build, styling and the room she is standing in all feed the same profile, so the portrait and the person do not contradict each other.
And none of it is permanent. Reopen the panel at any point, move a dial, and the change lands in her very next message rather than requiring a fresh character.