When we use the ls command ,there are a lot of things we need to understand.
Firstly, the output of the ls command:
As what is showed above,in the middle of the photo,there are 2 columns.First word is the user ownership of this file,and the second one is the group ownership of this file.
If we want to change the user,do it like this:
chown user directory
change the group:
chown :group directory