Since update to android pie, I see a green icon with APK in it, for apk files.
Only in Samsung file manager.
In other file manager I see the icon from application, beside APK name.
Can someone help me.
No, you'd have to contact Samsung and convince them to associate .apk with the app, not with the generic apk icon. (That's all that's happening, you're seeing a different icon - it's still an apk file and it will still install if you tap it.)