Go to Settings > Battery > Battery Optimization and ensure your new clock app is set to "Don't Optimize." This prevents the system from "killing" the app in the background, which can cause the time to freeze.
Ensure your phone is still set to "Use network-provided time" in the main system settings to provide a baseline for your new app. Conclusion
Better interfaces for tracking multiple international time zones simultaneously. Top Date and Time Apps for Android 1. Digital Clock Widget (Customization King)
Some apps sync with atomic clocks for down-to-the-millisecond accuracy.