50 / 60 Hz in Display control panel

["Ken Schunk" <kschunk@nycap.rr.com>]

I recently purchased an Apple IIgs, and I'm having one problem with it. I
can't
get it to display composite video correctly on most of the TV's that I have
tried.
Only an older B&W with a vertical hold control allows me to get a stable
picture.
I noticed in the Display control panel that it indicates "50 Hertz". I also
noticed
that my emulator software says 60 Hertz. Just what is this 50/60 Hertz item,
and would it have any impact on the composite video output?

Thanks
Ken Schunk