Unable to add javascript in Communities footer

Hi,

We are unable to update communities footer.Below is the code we are trying to add:

<script type="text/javascript">

setTimeout(function(){var a=document.createElement("script");

var b=document.getElementsByTagName("script")[0];

a.src=document.location.protocol+"//dnn506yrbagrg.cloudfront.net/pages/scripts/0021/3117.js?"+Math.floor(new Date().getTime()/3600000);

a.async=true;a.type="text/javascript";b.parentNode.insertBefore(a,b)}, 1);

</script>

Please let us know how we can implement this?

Regards,

Priya Gupta