From your question what I understand is, as soon as you log in you want class explorer(App) should open instead of recent (rules explorer).
To achieve that you can open pzExplorers data-portal and private check-out this rule.
you will see the tab-group layout included in the section. Click on App tab you will see the class explorer, save the rule pzExplorers and log-off and log-in you will see class explorer as default tab to focus.
As the rule is final you would not be able to make the changes application wide without unlocking the ruleset.