You can only have one prompt line at a time, that means you always active prompt will override all others.
Try changing your prompt line to a Text line instead.
change:
Prompt ( "Blow up all piles of ant eggs! " .. 6 - KillCount .. " left" )
to:
Panel(20,15,80,85)
TextColor(25,20,1,"Blow up all piles of ant eggs! " .. 6 - KillCount .. " left" ,0,255,0)
In the Panel line the 4 numbers are the co-ordinates of each corner of the background panel.
In the Text line the first two numbers (25,20) are XY positions of the text, the third number (1) id the font size, and the three numbers at the end (0,255,0) are the RBG colour of the text.
So you can move it to any position on the screen and change the font size and colour