Working with a list box in a fillable PDF.

I'm creating a fillable PDF (am currently using Acrobat X, but also have Live Cycle available). I need to create a list box with mutliple selections, which I've done, but I'm not sure what settings I need to apply or if coding is necessary to only have the selections show when done making the necessary selections. It's showing me the whole list with the selections highlighted. What's the best way to go about this?
Thanks!