TL;DR

Go to Beeper Android → Settings → Notifications → Configure Noisy/Default Notifications → "Pop on screen"

How to customize Pop on-screen notifications on Beeper Android?

While using Beeper Android, you should be able to receive “Pop on screen” notifications, but if for some reason you don't see them on your device, or you want to disable them, follow these steps to enable this feature.

1. Open the Beeper Android app.
2. Tap the top right gear menu → Settings
3. Tap Notifications
4. Tap Configure Noisy/Default Notifications
5. Toggle "Pop on screen" on or off.