Different template types/shapes support different connector (line) types, and the connector type can be selected from the drop-down selection on the contextual toolbar. For instance, if you're using a UML template, an ER template, or a Network template you'll be able to access different connector types accordingly.
UML Use Case Template
Entity Relationship Template
UML Class Template
Select a connector style
The default connector style for each template type is automatically set to enable faster visualization. But you can always change the style from the contextual toolbar to suit your requirements.
Select an arrowhead style
Select the arrowhead you prefer from the given styles on the contextual toolbar.
Simply change the arrow direction with a single click. This is helpful if you're drawing a complex diagram.
Flip the direction of the connector