This is just a template modification... *moving*
in registeradult-template you find this:
Code:
<td bgcolor="{firstaltcolor}"><normalfont>
<input type="radio" name="pmpopup" value="yes"> yes
<input type="radio" name="pmpopup" value="no" checked> no
</normalfont></td>
change it to:
Code:
<input type="hidden" name="pmpopup" value="yes">
then it is standart when they register, but can be changed in options after registration