Context configuration for Issue Picker fields follows the default Jira logic.
When created, Issue Picker fields have a default global context. To change the existing context or add a new one, see the steps below:
Select > Issues.
Under FIELDS, select Custom fields.
Go to the Issue Picker field, open the three dot menu > Contexts and default value > Add new context or Edit context.
In the applicable issue types section, select the issue types that you want this custom field to appear in.
In the applicable contexts section, select a global context or choose specific projects that you want this custom field to appear in.
Select Modify.