Once the campaign is created it will be assigned a pre-generated URL slug based on campaign name.
If you later change your campaign name the URL slug will not automatically change because there is a danger that such URL slug could be published elsewhere externally already by someone else (like for example in a tweet by someone) so link will not work if it URL slug changes.
However if you need to change URL slug or path for campaign manually you first need to make sure custom path option is enabled. You can do this by going to Portal Administration panel, then Portal Settings and then Campaign Settings. Under that tab, please make sure that option called “Allow Custom Path” is checked and save the settings.
Now the campaign path becomes changeable within the campaign creation process on “Basics” step as shown below. Either Website Administrator or Campaign Owner/Manager can change the campaign URL slug or path by setting it to anything they want and saving the campaign.

