Health data is always synchronized and saved in the users myPhonak account (cloud) when logged in. If the user changes their smartphone, the old health data should be visible as soon as the new smartphone is connected to the internet and the data has been synchronized.
If the user is logged out of their account, then the health data is not synchronized with the myPhonak account and for this time period the data is not visible in the app. If the user logs out meanwhile the data is synchronizing in the app, then this data will be lost.