I would guess you were “searching” and came upon an active frequency that you would like to “save” to a current or new FL? In which case try hitting the “E” key. That gives you a menu selection of “Quick frequency save?” Answer “Yes”. The menu now asks to Edit the Name or frequency, or Set a list of parameters. This Menu appears to be of no help until you choose “Delete Channel” which brings up another menu called “Quick Save Department”. I also found a menu called “Quick Save Favorites List”... but stopped researching your question at this point because it wasn’t turning out to be much of the shortcut you were looking for. It looks like there is a way to save and assign an FL to it but it appears that ability is set when you are in search mode-it asks if you care to save what you find.
Maybe it’s just too early for me. I will also be waiting for definitive answers to your question. Best I can do without researching the manual or looking back in the forums.