For Funtouch OS 3.0 and higher version, you can go to Settings>More settings>Permission management(Applications)>Default app settings to change the default apps. For Funtouch OS 2.6 and lower version, you can go to i Manager>App manager>Default app settings to change the default apps.

To claim Vivo warranty, you need to visit the nearest Vivo service centre with your device, purchase invoice, and warranty card. The service centre personnel will check your device for defects and provide necessary repairs or replacement if the issue falls under the warranty terms and conditions.