You can change the sort type when you touch the Capture Type-label. So tab on the "Capture Time"-label and you will see the other sort options like "Modified Date", "Custom Order" etc.
Hope that helps.
Thanks Guido. Sorted now.
Help! This is what I would like, but at my Ipad I've only see 2 options: "Capture Time" and "Modified Date". How do I get "Custom Order" or "File Name"?
Bingo! I found it: at the Ipad (Lightroom Mobile) there are 2 ways to see a collection: "Flat" or "Segmented". No idea what the benefits are, but it makes a difference in the possibilties to sort. If you look the "Flat" way, then you have the possibilty to sort by "Capture Time", "Modified Date", "File name", "Custom Order" and "Most Liked". If you look the "Segmented" way, you can only sort by "Cature Time" or "Modified Date".
Why on earth is this so difficult to find? It took me a whole day to find this out.....