Order of photos in the gallery

When you open gallery settings and after that open gallery images management section you can simply drag and drop images to change ordering of the photos in gallery on the front end. Another way for gallery sorting it’s ordering configuration option for the automatic photos sorting.
You can select one of the defined images ordering mode in gallery images settings. Photos could be ordered by name, date and some other parameters. Let me know if you’ll have some other questions about gallery ordering modes.