To change the ringtone on your Android smartphone, you'll need to open the Settings app and select the klingelton option. You'll see a list of preset ringtones, and you can test them by tapping the different options until you find one that you like. This will then be added to your ringtones list, and you can choose whether it's a default ringtone, a text tone, or a ringtone for a specific contact. You can then tap an option to save your new ringtone.
