how to set prefered operator with LUA about luatos HOT 3 OPEN

AT+COPS=?
+COPS: (2,"T-Mobile USA","TMO","310260"),,(0-4),(0-2)
OK
Available Networks:
Network Name->T-Mobile USA
Network ID->310260
Network Status->Current
AT+COPS?
+COPS: 0,0,"T-Mobile USA"
OK
Device is currently on "T-Mobile USA" network.
AT+COPS=1,0,"TMO"
ERROR
AT+COPS=1,1,"T-Mobile USA"
ERROR
AT+CREG?
+CREG: 0,1
OK
The device is registered in home network.
AT+COPS=2
OK
Network selection sucessful.
Updating the list...
AT+COPS=?
ERROR
Unable to find networks.
AT+COPS?
+COPS: 2
OK
AT+COPS=1,2,"310260"
OK
Network selection sucessful.
Updating the list...
AT+COPS=?
+COPS: (2,"T-Mobile USA","TMO","310260"),,(0-4),(0-2)
OK
AT+COPS=0,0, "TMO"
OK
Network selection sucessful.
Updating the list...
AT+COPS=?
+COPS: (2,"T-Mobile USA","TMO","310260"),,(0-4),(0-2)
OK
Available Networks:
Network Name->T-Mobile USA
Network ID->310260
Network Status->Current