Free Notifications app
Free Notifications is Xposed tool that is open source under the EUPL-1.2 license.New Android versions introduced finer settings for notifications. But they thought it was a good idea to exempt some Notification Channels from that customization, like the "Developer Options enabled"-Notification. Yeah, I know that. I did that. Now, please remove that notification.
This module enables customization for all Notification Channels again: vibrations, ringtones, importance etc.
When removing the module, the changed notification settings will stay as they were, only you won't be able to edit them anymore (until you install the module again).
If you want to get the default settings for system Notification Channels back, you can use the Reset all Notification Channels module.