Newbie question on schemas

I'm having a hard time understanding how APEX 5 works with schemas.  I'm used to developing applications in a master schema which has CRUD access to tables in other schemas.  That doesn't seem to work with APEX.  I created an application in that master schema, but when I go into Shared Components and try to create a List of Values on a table in another schema, that table isn't recognized, even if I precede the table name with the owner.  I've had similar issue with creating UI defaults.

I routinely need to access tables in multiple schemas.  I'm looking for a general guideline on how to approach building applications in APEX.  Do I need to create template-type applications under each schema that contain the UI defaults and List of Values for tables in that schema?  Will I then be able to reference those items from an application that is created in a master schema?

Thank you for any advice you can share.