[Q] Permissions change was not successful (root explorer) topic

Hello guys
Problem When Permissions


a-N7100 ROOTED
b-OS android 4.3 for mod note3

1- When Open Root Explorer
2-( R/O is selected)
3- Copy any app.apk to /system/app
4- Select and hold any app.apk /system/app and press Permissions and select:
5- User: Read, Write..etc
6-Permissions change was not successful. Please note that some file systems (e.g. SD card) do not allow permission changes

I hope the solution please