it did already show the correct IP in the IP Address box.
Thats because the select fields contains only the available IP addresses. For example if you would have added the new ones without deleting the old ones, every website would have shown the old IP address. Select fields work this way, so if a value is not available, the selct field shows just the first value.
Instead of editing each site, you could have replaced the IP address in the database and set the staus field to 'u' for every site.