Secure Minecraft worlds correctly?

I activated the Minecraft beta version on my phone, but did not download the beta update. Now I have left the beta and need to uninstall and reinstall Minecraft. But I'm afraid that my worlds will then be gone because that has already been the case. How can I secure my worlds so that they are never lost?

Before creating the world, specify an external storage location so that the world is not saved in the game folder (which is normally not accessible)

Alternatively, route the phone and copy the world from the corresponding game save folder.