Not able to Add Any Custom Ringtone
Using ringtones on the Moto G Power: You can use default notification tones or explore other options to personalize your MultiTimer application.. In case the alerts don't work, please email us at support@persapps.com, so we can look into your issue and assist you.
Set ringtone for app notifications
To change the sound for all app notifications:
Go to Settings > Sound > Advanced > Default notification sound
Do one of the following:
To change it, choose a new sound.
To turn notification sounds off, select None
To change the notification sound for a specific app:
Touch and hold the app icon.
Touch > Notifications
Touch the category for checkmarked notifications, then touch Advanced > Sound and select a unique ringtone, or set it to none.
Tip: To change your alarm sound, open the Clock app and touch an icon that looks line a clock. Then touch arrow down.
When you are unable to add custom ringtone on Motorola Moto G-family devices
This problem has been tracked since 2018 and is not app related, but system related.
The problem occurs after updates are installed - the phones revert to the default ringtone.
You can try some checkpoints here. Hopefully this will help:
Delete the original 'Ringtones' folder, manually created a new folder of the same name and then pasted a copy of the .mp3 into that directory.
Do the same with the 'Notifications' folder.
Go into safe mode and then reboot your device.