Placing multi-parts component into schematic

If I have a multi-parts(let's say 3 parts) component, I am placing them into schematic, it's labelled as U1A, U2A, U3A. I had to manually change U2A to U1B,and U3A to U1C so as to identify they are all from the same component.      How does it automatically have labelled part as U1A, U1B, U1C?   I cannot do that. 

Also, if I continue to place parts such as U1A, U1B, U1C, U2A, U2B, U2C(again, I had manually to change it),   how does it know U1A, U1B, U1C use the same footprint for layout and U2A,U2B, U2C use the same footprint?