Don't see how that could be possible if you are really using 4.0.12, as that wasn't implemented until 4.0.17. In any event, it is customer/main/checkout.tpl, this bit of code:
<TABLE border="0" cellpadding="0" cellspacing="0"><TR>
<TD>{include file="payments/ps_paypal_pro_express_checkout.tpl" paypal_express_link="logo"}</TD>
<TD> </TD>
<TD>{include file="payments/ps_paypal_pro_express_checkout.tpl" paypal_express_link="text"}</TD>
</TR></TABLE>