Although AQT displays procedures from all schemas, you can only manipulate procedures in your own schema (eg. where the schema name is your user name). The commands for creating and dropping a procedure do not allow you to specify the schema name; so they will be created / dropped from your own schema.
You should not alter / redefine a procedure that is in a schema different from your own. Procedures are implicitly created in your own schema. If you alter a procedure in a different schema, the changes will be applied to a procedure with the same name in your own schema instead, or if there is none, one will be created of that name.
Check Option doesn't appear to be set correctly in the SQLBase System Tables, so will not display correctly.