Xiaomi
Assign Alarm Functions to Volume Buttons auf Xiaomi
When an alarm goes off on a Xiaomi phone, the volume buttons can trigger an extra action besides the touchscreen controls. MIUI groups this behavior under the Clock app, not under the general sound settings, which is why many people never find it.
By default the system may leave the volume buttons without a function during an alarm, so pressing them does nothing at all. You can instead assign them to snooze the alarm or dismiss it completely, which is useful if you want to silence a ringing phone without unlocking the screen first.
One limitation applies regardless of which option you pick: MIUI does not separate volume up from volume down. Whatever action you choose applies to both buttons equally, so there is no way to make one button snooze and the other dismiss.
To change the setting, go to Clock ➔ Open the Menu ➔ Settings ➔ Additional alarm settings ➔ Volume buttons, then pick Do nothing, Snooze or Dismiss.
This setting only affects alarms triggered by the Clock app. It has no effect on media playback, calls or other notifications, so adjusting it will not change how the volume buttons behave outside of an active alarm.