Amazon RDS上的MySQL utf8mb4:全局变量设置正确但变量未设置

我正在尝试将我的Amazon RDS服务器转换为使用utf8mb4编码而不是utf8.我已经按照这里的指南进行了大部分工作(全局变量是通过RDS中的新参数组设置的),但我的系统变量设置不正确,这意味着我无法使用新的编码.

当我跑:

SHOW VARIABLES WHERE Variable_name LIKE 'character\_set\_%' OR Variable_name LIKE 'collation%';

我知道了:

+--------------------------+--------------------+
| Variable_name            | Value              |
+--------------------------+--------------------+
| character_set_client     | utf8               |
| character_set_connection | utf8               |
| character_set_database   | utf8mb4            |
| character_set_filesystem | binary             |
| character_set_results    | utf8               |
| character_set_server     | utf8mb4            |
| character_set_system     | utf8               |
| collation_connection     | utf8_general_ci    |
| collation_database       | utf8mb4_unicode_ci |
| collation_server         | utf8mb4_unicode_ci |
+--------------------------+--------------------+

这显然不正确,但是当我跑:

SHOW GLOBAL VARIABLES WHERE Variable_name LIKE 'character\_set\_%' OR Variable_name LIKE 'collation%';

我知道了:

+--------------------------+--------------------+
| Variable_name            | Value              |
+--------------------------+--------------------+
| character_set_client     | utf8mb4            |
| character_set_connection | utf8mb4            |
| character_set_database   | utf8mb4            |
| character_set_filesystem | binary             |
| character_set_results    | utf8mb4            |
| character_set_server     | utf8mb4            |
| character_set_system     | utf8               |
| collation_connection     | utf8mb4_unicode_ci |
| collation_database       | utf8mb4_unicode_ci |
| collation_server         | utf8mb4_unicode_ci |
+--------------------------+--------------------+

这是正确的,但由于某些原因,当我重新启动服务器时,这些全局值不会设置服务器.我可以在重新启动后手动正确设置变量,但我不明白为什么它们最初没有设置.