If it is the label and you do now need what is already defined, you can specify your label definitions using the "New Label" tab.

Ooops! I did not address where it "changes all the previously defined figures or tables to the latest selection" and, I am not sure I can answer that without seeing some portion of the document itself. Can you attach some portion of the document (removing any sensitive data) with the problematic issue for us to look at? It would be helpful.