If you create a new folder for your decks and wish to move some of the decks to new folder. Like if you copy a deck and want to make a modern version of a legacy deck. And you have them sorted that way.

It would a selection under tools or something like that called move and would list all of your folders

You can move a deck to a new folder. Once you create a new folder, you can drag and drop the deck to a new folder on the side column. I just did it on my computer using Safari.

Just tried it on my computer. Drag and drop works. I was attempting to do this on a tablet... Drag and drop does not work so well. I would suggest adding it to the tools anyway for phone and tablet users.