WhatsApp for Xiaomi Redmi Note 5A (Redmi Y1 Lite)

Random reboots on the Note 5A are usually caused by a misbehaving app, a corrupt cache, or an aging/swollen battery. First boot into Safe Mode (hold Power, then long-press the 'Power off' option until 'Reboot to Safe Mode' appears) to see if the reboots stop, which points to a third-party app you can then uninstall. Clear junk via Settings > Storage > Cleanup, and update MIUI under Settings > About phone > System update. If it still restarts, back up your data and do a factory reset (Settings > Additional settings > Backup & reset); if reboots continue even after a reset, the battery most likely needs replacing. See how others solved this on Reddit

The Note 5A ships with very little internal storage, but MIUI does not support 'adopting' an SD card as internal storage, so it can only be used as portable storage. To make the most of it, move apps that allow it: Settings > Apps > Manage apps, open an app, tap Storage, and use 'Change' to move it to the SD card where supported. Set the camera to save to the SD card in the Camera app's settings, and in Settings > Storage choose the SD card as the default storage location so new photos and large files land there automatically. See how others solved this on Reddit

The Y1 Lite is a budget device with limited RAM, so heavy multitasking and large modern apps will lag no matter what. Reduce the load: go to Settings > Apps > Manage apps and uninstall or disable apps you don't use. Unlock Developer options by going to Settings > About phone and tapping 'MIUI version' seven times, then in Settings > Additional settings > Developer options set Window, Transition, and Animator animation scales to 0.5x or off. Use lightweight 'Lite' apps (Facebook Lite, Messenger Lite) where possible and keep only a couple of apps open at once. See how others solved this on Reddit

On older low-RAM Xiaomi phones, MIUI's aggressive power management kills WhatsApp in the background and starves the camera, causing frozen video. Go to Settings > Apps > Manage apps > WhatsApp > Battery saver and set it to 'No restrictions', and enable Autostart for WhatsApp under Settings > Apps > Permissions > Autostart. Make sure WhatsApp has Camera and Microphone access in its App permissions, and close other apps before a call, since the limited RAM struggles to run the camera and several apps at once. See how others solved this on Reddit

The Note 5A runs Android 7 (Nougat) under MIUI, so newer apps that require a higher Android version are blocked or hidden in the Play Store. Install any available updates via Settings > About phone > System update, though this can't raise the Android version itself. If an app is genuinely too new, look for a 'Lite/Go' edition or sideload an older compatible APK from a trusted source like APKMirror that matches your Android version; note that very recent apps may simply no longer support this hardware. See how others solved this on Reddit