For Family Tree Builder albums, please note, that if you are using the Family Tree Builder to edit your tree you will not be able to change the order of the photos online. You will be able to do so however in the Family Tree Builder, under Photos > Albums. Click on the album you would like to reorganize, and drag the photos to the correct place in the photo list.
I am sorry, but the drag and drop don't work when opening an album online for one person, and all the pictures and documents related to that person appear. For me it looks like the order is quite random. I wonder what it is that decides the order. The albums are not made in Family Tree Builder, and drag and drop works well for the other albums on my site.
Now I have discovered that when fetching the album for a person from the Family Tree/ People or Photos And Videos/Find pages, it is possible to sort the pictures according to title, date or place. This is great feature!
Could it be possible, in the future, to have the same feature when fetching the album for a person by clicking on the name in the list (under the albums) on the Photos And Videos/Albums page?
Please note, that I have already forwarded your request to the appropriate team for consideration.
However - you are correct.
Currently, and you've mentioned - you can also use this feature to view the photos for each person in your family tree, by entering your family site > photos & videos > find > click on any person in "photos of people" section >arrange the photos by the preferred criteria.