Because SPDEF only creates a new template. What you're looking is SPCHR.
SPCHR Management number,[U],[V],[W],[H],[Attribute]
In your case, it would be:
SPCHR 0,16,32,16,16,#SPSHOW+#SPREVH
You should look for the Instruction List, which contains all the commands with examples and explanations:
http://smilebasic.com/en/reference/
Or you could place the text cursor over a command and press the "?" button on the touch screen.
