WYFF definitely used a jingle with the lyrics “Your Friend Four”. I think the call sign may have still been WFBC at the time, and the name sounded so good the station changed the call sign.
As I recall, the jingle sounded great … I remember it sounding better than the Your Friend 3 jingle here … but then again maybe the memory is just fuzzy.
The YF3 jingle singers sound a bit European … I don't recognize them as JAM singers. And I don't remember that sort of European accent on the YF4 jingle.
Maybe Jon can help us out here.