In today's digital landscape, ensuring the multi-screen compatibility of applications is crucial, as users frequently access services across various devices such as desktops, mobile phones, and tablets. With nearly 7 billion individuals using mobile devices, it is vital for applications to function seamlessly on these platforms to maintain user engagement and competitiveness. Testing for multi-screen behavior involves setting up environments that consider the application's usability and complexity, with options ranging from emulator plugins for simpler applications to real-device testing for more intricate ones. Cloud platforms like LambdaTest provide virtual environments for testing cross-device and cross-browser compatibility. Key challenges include ensuring responsiveness, clickable elements, font readability, and the proper functioning of advanced features such as gesture control and fingerprint scanners. Due to the diversity of devices, especially within the Android ecosystem, testing strategies should focus on major devices and browsers, and consider regional device preferences to optimize user reach. Cross-device testing is essential to prevent user dissatisfaction and application abandonment, emphasizing its importance prior to production deployment.