You can search for a specific port in the design hierarchy by using the Design Hierarchy View.

Press the Select Top button and pick one of the available design tops.

The ports panel is displayed in the bottom half of the view.

In the instances filter text box, type the name of the port you are looking for, preceded by the dot '.' character. The instances that contain the port are bolded. The ports are also bolded and promoted to the top of the ports pane.