If you do not see the Individual Card Settings controls, turn off Print Mode.
The individual card sizing drop-down allows you to override the global settings for the card sizing:
The individual card sizing drop-down gives you all of the card sizing options from the global card sizing drop-down:
This gives you the control, for example, to print a more complicated ace on a bigger card and the ace's supporting mini-swarm on smaller cards:
You can reset all cards to have the same size by resetting the global card size drop-down.