Swf. reset

i have 2 mc’s(load movie destination) in my swf. file.
i have several buttons, 1 loads to an mc while the other 5 load to the other mc.
the problem is when the “1” gets loaded it’s fine but when another button is pressed the “1” movie doesn’t disappear when the other one loads.
make sense? iv’e searched this site but can’t seem to find any answers.
can someone please help.