You have to modify the plugin-file for changing your Google+-ID (Placeholder: YOUR_ID) in it.
NOTE: There are two lines you have to change!
Line 14
<link href="https://plus.google.com/YOUR_ID" rel="publisher" />
Line 33
<div class="g-plus" data-href="https://plus.google.com/YOUR_ID?rel=publisher" data-width="300" data-height="69" data-theme="light"></div>
You have to modify the plugin-file for changing your PIWIK-Url (Placeholder: PIWIK_URL) and PIWIK-Side-ID (Placeholder: PIWIKID).
NOTE: There are three lines you have to change!
Line 16
var pkBaseURL = (("https:" == document.location.protocol) ? "https://PIWIK_URL/" : "http://PIWIK_URL/");
Line 20
var piwikTracker = Piwik.getTracker(pkBaseURL + "piwik.php", PIWIKID);
Line 24
</script><noscript><p><img src="http://PIWIK_URL/piwik.php?idsite=PIWIK" style="border:0" alt="" /></p></noscript>