When changes are made to your bot they always need to be published before they come into effect.
Instructions
Click on the purple Publish button in the bottom of the page.
A popup appears to indicate that your bot is being published and trained.
I don't see a Publish button
The publish button isn't available on all pages. If you don't see it, go to the content section to be able to see and click on the button.
I see the Publish button, but it is greyed out
There can be two reasons for the publish button not to be clickable. The first is if there are no changes to your Smart App compared to the latest published version. The second is if your bot contains errors that need fixing.
Either fix issues manually, or revert to the latest published version to undo your changes. You can do so by using the menu next to the Publish button.