A. 1. Ensure you are using the correct username and password. If you’ve forgotten your password, use the 'Forgot Password' feature to reset it. 2. Check your internet connection; try switching between Wi-Fi and cellular data. 3. If you have two-factor authentication enabled, ensure you have access to the second factor (like a text message or authentication app).
B. 1. Clear the app's cache as described above. 2. If the problem continues, try uninstalling and reinstalling the app to reset any corrupted data.