I had to change the name of a parent page, and its URL automatically updated to reflect the new page name, but the child page's URLs did not update. I've changed page names before and they've always updated automatically (causing me to have to fix all the broken links, of course), though it usually takes a couple of hours for them to change. But it's been a day and they have not changed. I don't have access to the Host Settings referenced in the DNN user manual which apparently is where the Friendly URL settings are. But I do have access to all the site files. Any advice on how to force them to update would be appreciated. I am not well versed in back end coding; an ad agency built this site, and I was brought in to get it ready for launch.

It's not good advice to switch off friendly urls - that is a host-specific recommendation and for the vast majority of DNN sites, friendly urls work just fine.

Can you link to the site that is showing the problems ?  It is hard to know what the exact problem is without seeing the site.

Incidentally, once you change a parent page, the child pages should automatically update immediately.  All of the urls are built 'in real time' so you should always have the latest urls in your page.