There's no way to sort directories. I'm not even sure how their currently sorted, it seems kind of random. You might want to suggest that in the new ideas section. I would definetly vote for that feature. It would also be nice to be able to choose and omit directories. If you do visit the new ideas section please vote for the ability to open .psd files in PS Touch. So far thats my biggest issue with the app.
As far as updating you need to go to the Samsung App store to update the preinstalled PS Touch. There is a icon for the app store in your apps menu. Then search for PS Touch, which sould let you update from there. If you have any files that you are working on you might want to make sure that they are uploaded to the adobe cloud. Not sure if it will delete them when you update.
Thank you for your reply.
Where do I find this Adobe 'Idea Section' you are referring to to put in my suggestion.