Is there a way to show the invoices to which the customer payment is applied to in the customer statement?

If this is what you mean, then you need to make sure your PDF code looks like this and uses line.description: <table class=“itemtable” style=“width: 100%; margin-top: 10px;“><!-- start items --><#list statement.lines as line><#if line_index==0> <thead> <tr> <th colspan=“3”>${line.datecol@label}</th> <th colspan=“3">Due Date</th> <th colspan=“5”>${line.description@label}</th> <th colspan=“4">PO#</th> <th align=“right” colspan=“3">${line.charge@label}</th> <th align=“right” colspan=“3">${line.payment@label}</th> <th align=“right” colspan=“3">${line.balance@label}</th> </tr> </thead> </#if><tr> <td colspan=“3”>${line.datecol}</td> <td colspan=“3">${line.duedate}</td> <td colspan=“5”>${line.description}</td> <td colspan=“4">${line.otherrefnum}</td> <td align=“right” colspan=“3">${line.charge}</td> <td align=“right” colspan=“3">${line.payment}</td> <td align=“right” colspan=“3">${line.balance}</td> </tr> </#list><!-- end items --></table>