Found this on Google:
Go to the Device Settings
Tap "Apps"
On the top right, tap the gear icon
Under Advanced, chose "Draw over other apps"
Find the app in the list and tap it
Toggle "Permit drawing over other apps" to ON.
*Note: For Samsung devices running Android 6, this setting has been moved to Settings > Applications > Application Manager > More > Draw over other apps
**On newer Samsung devices, such as the Galaxy S7, the "Draw over other apps" has been renamed to "Apps that can appear on top".
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