Why can't I customize the order I view my photos in the Gallery?

[AC Question]

I recently moved from an iPhone to the Galaxy S6 edge and was a happy camper until *gasp* I tried to create alumbs of the photos I transferred from my old iPhone. I create a new photo album everytime I go to the gym so I know what workout I'll be doing before I walk through the doors. On the iPhone you're very easily able to grab photos and move into a specified order, on the Galaxy, however, you are not. Does any one know how I customize the order of my photos? Or of an app that I can customize the order?