You can customize arrangement of UML model elements on your diagrams automatically or manually. 

UML modeling enables you to manage diagrams with automated layout features that optimize the diagram layout for viewing or printing. Nodes and links on a diagram are arranged according to a certain algorithm. 

There are several diagram layout algorithms available. You can apply the same algorithm for the entire model, or different algorithms to separate diagrams. 

Each algorithm has a set of specific options defined in the Modeler(level)DiagramLayout category of the Options dialog window.  

It is also possible to lay out a diagram manually by moving and resizing nodes and reshaping links. You can also lay out your diagram automatically, and then adjust arrangement manually.