From your description, it seems like you did not add a Portal field of the Application table to your Applicant layout.
Based on your relationships that you described, you should also add an Assets portal to the Application layout and the Bank Accounts and Insurance Portals to the Assets layout.
The Application Portal allows you select, view, edit, and optionally add one or more records from the Application table while remaining on the chosen Applicant layout. Is that your goal?
P.S.: Did you create the table joins using the relationship graph of Manage>Database…Relationships tab?