To hide the "running in background" alert specifically:

Fix plugged the phone into a tangle of cables connected to a bulky tower PC. "You downloaded a 'Fix' that needed a fix. Classic irony. The file is locked because it thinks it’s a system app. It has permissions that user apps shouldn't have."

Run:

Before downloading any third-party tools, try the native Android method. Most modern versions of Android (especially 8.0 Oreo and newer) allow you to silence or minimize these alerts without killing the app. Long-Press Strategy

Persistent notifications are a trade-off: