Is there a way to setup all video and still images to auto-fit in the overlay box?

To all of you who read this and maybe, possibly can't make a lot of sense, or maybe if my questions seem not to be very logical please be patient with me, I am a novice and poking my way into learning, doing so only relying on kind folk like you here and all over the net.
Is there a way to setup all video and still images to auto-fit in the overlay box without going clip by clip and cropping which doesn't even seem to work with images? The footage I have has been downloaded from different sources that have different resolutions/ratios. All the video clips can be sized separately, but is there a better, easier, automated maybe way to autofit?

Overlay box? What's that? Do you mean making each image fit inside of the video Frame? I'd not crop, but resize them.

Yes Ben, thank you, that's exactly what I mean. How do I resize all clips that are from different sources and different sizes (formats) to fit in the video frame. Also can the still images be fitted in the same way?

Two ways:

You can select the clip in the Timeline, in the Inspector's Video tab, look at the Spatial Conform section. Try "Fit" and "Fill". Fit will adjust the Scale parameter automatically so that the whole image fits inside the video frame. Fill will adjust so that the image is resized enough so that it's most narrow aspect (height or width) fills the frame. You can select multiple clips in a Timeline and change this parameter for all of them at one time.

The other way is to select the clip in the Timeline, and in the Inspector's Video tab, look at the Transform section, and manually adjust the Scale parameter yourself.

Thank you much Ben, I will try that!

Ben I am using FCP 7, and I can't find the Spatial Control anywhere in the inspector's video tab. Is it possible you were talking about a different version of FC?

Dang it! Yes, I was talking about FCP X.

In 7, in the Preferences, you can set it so that stuff is fit to inside the frame size automatically. You'll have to manually adjust the Scale parameter.