There is a diffenrence difference in how MLCS configurations are displayed between Server / Data Center instance instances and Cloud istanceistances.
Server / Data Center
In a Server / Data Center instance instances you can find the MLCS configuration in the Issue settings. To show the configuration, Custom Fields, click the wheel on the top right corner and click on Issues. Then, click on Custom fields to show a list of your custom fields. Click on the three dots and choose Configure context. The configuration will be shown unther under the voice “Options:”, here is an example:
...
Jira Cloud
In Jira Cloud, the configurations of your MLCS Multi-Level Cascading Select custom fields is are stored in the MLCS app. To see and manage the configuration, click the Settings dropdown menu and click on Apps. Find “MLCS Cloud” and click on it. you will see the configuration with all your options. By default, they are assigned to any Multi-Level Cascading Select field. To connect a configuration to a specific MLCS custom field, click on the Element Root (the first level option) and assign it to your field. This will make the selected Element Root unavailable to the other fields.
...