Hi im a newb so please bare with me, i hope someone can help
I'm trying to make a short animation with  text , and then later i want some more text to appear underneath it .. 
for storytelling and that sort of thing.

maybe there is a better way to do this. but this is how i tried to do it..

i made two pictures (.png), 
i figured.. i could use these pictures as textures on a floor object in iclone6 and just change the texture  later in the time line..
the first picture has the first line of text, and then a second picture has the rest of the text .

My problem..
 Every time i try to change the texture  to the second picture,  it changes the first texture as well. even though i am later in the timeline

the diffuse option in texture settings is hightlighted in green, its my understanding if any area in iclone6 is highlighted in green i can animate it?
but its not animating my changes? so i must be doin something wrong ...is there anyone who can help me?