Update join_buffer_size,thread_cache_size… but not save

Please help me!
When I change join_buffer_size with command:

mysql> SET global thread_cache_size=4;
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW GLOBAL VARIABLES LIKE 'thread_cache_size';
+——————-+——-+
| Variable_name | Value |
+——————-+——-+
| thread_cache_size | 4 |
+——————-+——-+
1 row in set (0.00 sec)
Click to expand…

But when I use service mysqld restart, then not save…

[root@Centos ~]# /etc/init.d/mysqld restart…
Click to expand…

Update join_buffer_size,thread_cache_size… but not save

See original post by nguyentien