Quicktime playing movies off centre

Question

Quicktime is playing my movies off centre!  VERY frustrating!  I've tried altering screen size - no luck.  I've tried exporting to iTunes - encounters an error.  These movies worked fine on PC media player. 

Answer 1

I'm using the Quicktime app and my movies are being played (and opened in Quicktime) off centre - titles and the picture is being cut off on the right.
Still trying to determine if you are referring to the QT 7 or QT X display window or the actual content within the window. Have therefore posted an image below:
Does he QT player window look like this? That is is the player window itself playing beyond the edge of the display screen or is the QT player window located in the center of your monitor screen. In the image above, the QT player window has been moved beyond the display limits of the monitor and merely needs to be dragged back into the monitor display area by clicking on the QT player window and dragging to a more centralized viewing position. This is the simplest problem.
Unfortunately there could be other possibilities here:
QT also allows the embed of display values which allow the content to be offset within a defined QT display window. QT normally prevents a users from manually setting negative value here, but I suppose it might be possible to make changes using special utility apps which may or may not result in a "cutoff" of displayed content with the player window located in the center of a screen.
Another possibility is the application of an embedded mask.
Lastly, there the movie and/or PLIST file for the app could be corrupted.
Example of a masked file played in the VLC player which ignores the mask
Same file as played in the QT 7 player with a mask to "chop off" the top and bottom of the display area during playback
As indicated by the samples above, files can be edited (embedded with settings or masks) that are ignored by third-party players but which can affect how a file plays in QT based apps in terms of the display area or when playback starts and/or stops. While I doubt you would forget performing such edits, I mention then as possible ways in which a file could play one way on a PC and differently in QT or differently in different QT players.
I can't open the movies in iTunes and can't export the files.
This normally implies that the files were not encoded with compression formats compatible with iTunes and/or mobile devices. Unfortunately, this contradicts the ability of you files to open and play (albeit off center) in the QT X player under mavericks unless you failed to mention that the files were being automatically converted by the QT X player and, in which case you should save the converted copy of the file for use in iTunes or with mobile devices.
And I have no idea if the media contains embedded display offsets (I don't even know what that means).
The QT 7 Pro keyed app contains track level property settings that allow a user to move graphic content around to different locations within the QT 7 player window. The is handy when creating a "movie within a movie" or "movie within a still image" graphic effect. QT 7 Pro can also scale the video track content independently as well as move the scaled content around the display area. (E.g., I have created movies that play within the display area of a TV set in a still photo or played on a monitor screen of a second movie playing in the background of my clip.) However, based on your comments, I doubt this is the problem here.
I just had these files on my PC and recently brought a mac.  These files were fine on my PC.
It is always helpful to indicate what kind of movies we are talking about here in terms of file container of data compression formats within the file container as the combination of the two may affect how a file plays and/or converts—especially under Mavericks which includes totally new embedded media playback structures within the Mac OS.
Is there another app I should be using?
Since you are dealing with content possibly created on/for PC playback, you may want to try the free VLC player download on you Mac. It employs the FFmpeg codec package which better supports PC media formats.
I've looked through the settings for quicktime and there are no options available for chaining the video dimensions or something like it.
If you are saying the "View" menu playback settings and/or keyboard shortcuts do not work, then either the app or the app's PLIST file is most likely corrupt.