Question about Aspect Ratio

I have a question about aspect ratio. First off, I am sloooooow to
technology, and only bought a Blu Ray player early in the year.
I was using (and still enjoying) a huge, 46-inch rear projection TV
from the '90s (it makes older films look better, and I don't have
side-bars when I watch, say, "Alfred Hitchcock Presents.") In any case,
I have yet to purchase the Blu Ray of this film, which I watch every
year at this time on DVD.

At any rate, when I attempted to watch this film on my new flat-screen
TV last night, I noticed that the "widescreen" side of the disc looked
"stretched", so I changed my TV screen to "normal" for a 1.33 aspect
ratio. But all it did was make the picture much smaller, framing it
in "window-box." That also looked wrong. Finally, I settled on "Zoom",
which filled the screen. The pic quality looked much, much better.

I noted that the film was shot in "superscope", which to me, seems
wider than 1:33, but not as wide as widescreen.

Can anyone explain this? I went to a lot of trouble to find the "right"
screen. And how is the Blu Ray framed???