Set permissions to an app?

Hi,

I have followed this guide to create a Todo app. 

The app works fine but now I realized that evry user can see this Todo list. So I wonder if it is possible to set this app to show just the current connected user's todo list? 

Or if is not, is there another approach to create a ToDo list? 

I am also looking for a way to create a notebook where users can save theirs notes. 

Best regards

Americo