If you insert cross-references into topics and then later edit the formats for those cross-references (or make other changes in the project that might affect them), you can update the cross-references in a topic. By updating cross-references, you are essentially "refreshing" them so that they reflect any pertinent changes in the project since you inserted them.
Updating cross-references is not a mandatory step. When you generate output
How to update cross-references
Select Tools>Update Cross-References.
The Update Cross-Reference dialog opens, displaying the destination topics of your cross-references.