Writing an XML using XmlSerializer

I am using XML

I am trying to set the prefix to NS1 throught the whole document, so i used :

XmlSerializer serializer = Xml.newSerializer();
StringWriter writer = new StringWriter();
try {
    serializer.setOutput(writer);
    serializer.startDocument("UTF-8", true);
    serializer.setPrefix("ns1", "http://ift.tt/1dosXhP");
    serializer.setPrefix("xsi","http://ift.tt/ra1lAU");
    serializer.startTag("ns1" , "HBA");

    serializer.startTag("ns1", "TITLE");
    serializer.text(cd.title);
    serializer.endTag("ns1", "TITLE");
    // and till the end

but when i check the XML file i see this :

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?><n0:HBA xmlns:ns1="http://ift.tt/1dosXhP" xmlns:xsi="http://ift.tt/ra1lAU" xmlns:n0="ns1"><n0:TITLE></n0:TITLE>

so here as you can see the prefix is set to N0 not NS1 as i require. also the XML is writen side ways, but i would like to have every tag on a separate line :

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
<ns1:HBA xmlns:ns1="http://ift.tt/1dosXhP"   xmlns:xsi="http://ift.tt/ra1lAU">
<ns1:TITLE>TEXT</ns1:TITLE>
<ns1:NAME>TEXT</ns1:NAME>