The Swisscom Home App is only available in the Swiss App Store.

You can change the country at IOS as follows:

1. Tap "Settings" > [Your name] > "iTunes & App Store" on the device.
2. Tap on your Apple ID and then tap on "Show Apple ID".
3. Tap Country/Region, then tap Change Country or Region.
4. Select a new payment method and enter your new payment details and billing address. 

You can change the country in Android as follows:

1. Open the Google Play Store on your mobile device.
2. Tap the three dash Account Country and Profiles menu.
3. Tap the country you want to add an account to.
4. Select a new payment method and enter your new payment details and your new billing address.