How to change the RSS Feed Settings:
Head over to the left side fo the dashboard and click Automation.
(Check out this guide on how to create a new RSS automation)
Once you have been redirected to the Automations page go ahead and click Edit Configuration.
From here you have to Pause your current automation to change the current settings, so go ahead and click Pause automation.
Now you will be able to change all the necessary details in your RSS Feed, so go ahead and change whatever is necessary.
After you are done scroll down and click Update and set live.