2
Sometimes this is hardcoded into your theme.html unless the user is actually logged in, then it changes to the proper name.
<{if $xoops_isuser}> <img src="<{$xoops_imageurl}>title_icon.gif" width="22" height="22" align="absmiddle">Welcome <a href="<{$xoops_url}>/user.php"><{$xoops_uname}></a>. <{else}> <img src="<{$xoops_imageurl}>title_icon.gif" width="22" height="22" align="absmiddle">Welcome guest. Please <a href="<{$xoops_url}>/register.php">register</a> and become a member.
<{/if}>
I think the Guest name can be changed in your admin for anonymous users.
*Code taken from my site, your's may vary depending on the theme used