Samsung
Change Alarm Sound auf Samsung
On older Samsung phones, the alarm tone was a single global setting. In Samsung One UI, every alarm you create keeps its own sound, so you can assign a soft tone to a weekday wake-up alarm and a louder one to a backup alarm.
The setting lives inside the Clock app, not in the general sound settings of the phone. This trips up a lot of users, because changing the tone under Settings ➔ Sounds and vibration only affects notifications and ringtones, not alarms.
To change the sound for one specific alarm, open Tap on Clock ➔ Choose an Alarm ➔ Tap on Alarm sound ➔ Tap on Ringtone ➔ Set an Alarm sound. Confirm with Tap on Back ➔ Tap on Back ➔ Tap on Save to store the change.
Alongside the built-in ringtones, you can also add a custom alarm tone from your own audio files, which is useful if none of the standard sounds work for you. If you want to change the volume or vibration pattern instead of the sound, those options sit in the same alarm edit screen, right next to Alarm sound.
If an alarm still plays the wrong tone after saving, check whether you edited the correct alarm entry, since Samsung One UI allows several alarms with similar labels and times.