I don't know how many of you out there want to do this, but here is how I fixed mine:
1. Open/Edit mod_utchatwhosonline.php in your editor of choice (Under the Modules directory)
2. Find the first line that shows $info = "<strong>%d</strong> "._UTCHAT_MOD_WHOSONLINE_USERSONLINE." ".$room; (***It is line 55 in mine***)
3. Change the _UTCHAT_MOD_WHOSONLINE_USERSONLINE to Users
4. Save and Upload
NOTE: Make sure you change only the first occurrence of this. The second occurrence actually shows who's online.
This was killing me trying to find it, and there is nothing listed in any of the forums (except the French ones). Hope this helps someone...