Change the size of temp file

How to change the size of temp file.

SQL>  select FILE_NAME,  MAXBYTES/1024/1024 MB from dba_temp_files;
FILE_NAME                                                                          MB
------------------------------------------------------------ ----------
/u01/app/oracle/oradata/new_location/temp01.dbf                    3072
SQL>
SQL> alter database tempfile '/u01/app/oracle/oradata/new_location/temp01.dbf' autoextend on maxsize 4G;
Database altered.
SQL> select FILE_NAME,  MAXBYTES/1024/1024 MB from dba_temp_files;
FILE_NAME                                                                           MB
------------------------------------------------------------ ----------
/u01/app/oracle/oradata/new_location/temp01.dbf                    4096
SQL>