how to change the values of Capacitors in a global way ?

Hi, If I want to chage the values of 20 capacitors in a simple way, how to do it ?

For example: 20 capacitors are in few level of drowing and I want to define the values of the capacitors in a global name.So if I need to chage the values of them, all I need is to change in one place. Can someone know how to do it ?

Thanks,

Henry