Customizing notifications on Android 8.0 and above through Notification Channels
Google introduced Notification Channels with Android Oreo. The goal of these channels is to remove the ability for the developers to customize your notifications, and provide that customization to the user through a set of system-level settings.
On the user's side, what this means is that you can no longer customize notifications within the app. The system is now in charge of all of the notification features. Most manufacturers will allow you to customize the ringtone, vibration, importance, Do Not Disturb mode behavior, among other things. Some manufacturers allow for different levels of customization. In other words, not every phone will be the same.
Default Notification Sounds and Customization
To customize the default notification alerts, you can go to Settings and select the Notification Customization preference. This will allow you to make changes to the default conversation notifications channel. Whenever a notification is posted that you have not done any individual conversation customization for, it will use the settings you make for this channel.
Individual Conversation Notification Customization
Customizing individual conversations is similar. If you open a conversation, then access the Conversation/Group settings from the 3-dot menu, and use the Conversation Notification Customization preference, Pulse SMS will create a new notification channel for that contact (or group). Once this channel is created, this conversation will not use any of the settings that you defined for the default channel. You can now customize this conversation separately from the others.
If you want to go back to using the default conversation notification settings for this conversation, you just need to delete the custom channel that was created. To delete this channel, simply access the Conversation/Group settings again, and select the Restore Default Notification Settings preference.
Tips for Notification Channels
If you think something got messed up with your configuration, you can reinstall the app to reset all of these channels.
You can long-press any notification to access the notification channel settings for the channel that posted that notification.