Found under: Settings > Set Actions > Rename
Whilst current sets are only available on the current device, these can be saved and then later loaded from set files.
All set files are stored in the /OpenSong/Sets/ folder. To better help organise your sets, OpenSongApp allows you to use categories. These are simply appended as text to the beginning of the set file name (compatible with the desktop version of OpenSong). Selecting a category will find all matching sets and display them on the screen. The MAIN category is for sets that haven't specified a category.
To rename a set, click on it from the list and then change the name / category. If the new set name already exists, you will also need to tick the 'Overwrite existing item' option.