Become server administrator:

After creating your server, the first thing you will want to do is become an administrator (OP). To do this, start by stopping the server from the options in the lobby: Options>Persistent server>Stop the server

Still from the lobby, now open the file manager (FTP client): Options>Persistent server>Open the file manager

In FileZilla, edit the file "/starbound/storage/starbound_server.config" and find the following lines:

"serverUsers" : {
},

Replace them with these lines without forgetting to enter your identifiers in place of the values myPseudo and myPwd:

"serverUsers" : {
    "myPseudo" : {
      "admin" : true,
      "password" : "myPwd"
    }
},

When you save a file with your text editor in FileZilla (the integrated FTP client), a window opens asking you to validate the upload of the edited file to the server. It is easy to forget because the window does not come to the fore and this error is the source of some confusion.

Restart the stopped server before connecting to it in game without leaving the lobby.

In the game chat, enter the command "/admin" to activate your permissions.

You are now a server administrator and can use all the commands authorized by your new privileges directly from the game chat: https://starbounder.org/Commands