Often a large model has many layers of hierarchy. You can see the hierarchy depth of each module at the top of its Diagram window by setting a preference. Select Preferences from the Edit menu to display the Preferences dialog.
If you check the Show module hierarchy box, the top of the active Diagram window displays the module path down to the current module:
You can jump to any parent or ancestor module by clicking on its name in the strip. When you click on an arrow, a tree menu displays other modules at that level and enables you to quickly navigate directly to any other module in the model: