DaveC wrote in
:

Olympus FE-20 p&s digicam.

Holding the camera up and using the display as the viewfinder, the
exposure looks normal. Pressing the shutter button results in an
overexposed photo.

It doesn't matter if the flash is on or off; the resulting photo shown
on the LCD display is always overexposed.

Changing the exposure setting does have a little effect on the
exposure.

I'm a bit confused; if the "before the shot" view in the display is
accurate, why would the exposed photo be different?

What makes you think that it is accurate? Cameras adjust the viewfinder
image to make things easier for the photographer - in the dark they make
show the preview as lighter to make it easier to shoot and in a sunlingt
darken it.

So, cameras do lie before the shoot... But note that you should not trust
the "after"-image either as it will be different to what the photo will
look on your computer. Also, brightness of most LCD's can be adjusted.
Check what the photos look on your computer, adjust the LCD and then
you'll know what is accurate and what not.

And if your camera can display a histogramm, try using that to judge the
photograph's brightness.