CookBook automatically syncs your recipe data every time you change and save it to ensure the most up to date version is always held in the cloud, every ~20 minutes, every time you start the app and every time you return to the app after a period of time.
You can also manually trigger syncing by clicking the 'Sync Device' button on the top of the side menu in the app. You will need to manually press sync on your other device if you would like it to show up immediately.
CookBook has been designed this way to conserve power so it's not always connecting to the network and looking for changes to your account.
Please note the only thing you cannot share across different devices is the shopping list - this is something we plan to change in a future update so that it will sync across devices too!