The fields can be changed but not save.
First try to fully disable strict mode for your tables. If this will not help you try second method.
[mysqld]
sql_mode=””
[mysqld]
sql_mode=ONLY_FULL_GROUP_BY,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
Where to find this config file? It depends of your server configuration. Usualy:
/etc/my.cnf,
/etc/mysql/my.cnf