CrossSearch results are sorted by relevancy, by default, but there are a couple of options to change this.
You can use the date slider in the column to the left of your search results to adjust the time range covered in the results, then click Update.
Or you can use the Relevance pick list at the top-right of the results to change to Date (newest) or Date (oldest) to re-sort the entire results list. Before doing this, you might want to reduce the size of a large results list by adding more search words, or apply some of the limits and filters in the column to the left of your results, such as selecting or excluding Subject terms, or limiting the results to particular formats or types.
You can find more tips on using CrossSearch on the Library's Help with CrossSearch page