URL path settings not supporting more than one level I'm trying to edit and create content on my inherited Drupal site and when I enter an address into the "URL Path Settings' URL Alias" field, it will not save the first part of the desired URL.
For example if I enter "firstpart/contentname"
it just saves "contentname" instead of the full hierarchy.
That's strange. If you edit the URL alias manually, it shouldn't be automatically changed unless you bulk delete and update your URL aliases in Pathauto.

Have you checked your Pathauto pattern settings (/admin/config/search/path/patterns) to see if there is something overriding your changes?

You said that you inherited the site. Are there any URL/path-related modules that your predecessor has enabled?