To change the default URL of a post type, please follow the steps below.
Go to My Content >> Edit Post Settings. Search and click Edit for the post type that needs to be updated.
Scroll down, find the URL Permalink field, update the URL as desired.
Important: Make sure to not have any spaces or special characters in the new URL.
When Saving the Post Type, a message will display to confirm this change: "The URL of this Post Type is being changed from classifieds to brilliant-classifieds. This action will also update the slug URL of all associated posts."
This means that already created posts showing under the URL /classifieds now are going to display under /brilliant-classiffieds.