Change Sharepoint sub-site url, but form posts to old url

I built a sub-site and later discovered that the url needed to be changed. In the site settings, SharePoint Online lets you do this for sub-sites (not site collections). I changed it and everything seemed to be fine until I tried to add an item to a list. When I click submit I get an error page and when I looked at the url I realized that it is still posting to the old url. I can't find a way to change that url. Anyone know where that might be hiding or if it is a bug?