Why per-app sounds help
When every app shares one default tone, a message, an email, and a game alert sound identical. Assigning different tones lets you recognize the source instantly.
It also reduces the need to check the screen constantly, which is useful during work or meetings.
Keep each tone short. Recognizable 1 to 3 second sounds are easier to tell apart than long clips.
Change it in app notification settings
Open Settings, then Apps or Applications, select the app, and choose Notifications. Inside, look for a Sound option tied to the notification channel.
Some apps expose several channels, such as messages, groups, and calls. Setting a tone per channel gives you even finer control.
If your downloaded MP3 does not appear in the picker, move the file to the Notifications folder and open the picker again.
A practical assignment strategy
Assign stronger tones to important apps and quieter ones to games or utility apps.
Two or three distinct sounds are usually enough to build a useful mental map. Too many similar tones defeat the purpose.
Review the assignments occasionally. When an app updates, its notification channels can reset to the default sound.
Frequently asked questions
Which apps allow a custom notification sound?
Most Android apps with notification channels do. The setting is usually under Settings, Apps, then the app's Notifications section.
Why did my custom tone reset to default?
An app update can recreate its notification channels. Reapply the tone after a major update.