The MPEG Layer 3 audio compressor provides reasonable quality in a small size and is available on most computers. However, sometimes, using this compressor may result in synchronization problems. Change the audio compressor to "Uncompressed" and then try making the movie.
The video and audio may also go out-of-synch when the video frame rate of the output movie differs significantly from the original movie. If there are multiple video clips added to the timeline, the "Auto Select" feature selects the highest frame rate to preserve video smoothness. Try keeping the frame rate as close to the original video clip as possible.
To change the dimension of the video, point to the File menu and click New Project. Either select a pre-defined dimension or a custom dimension. If you are making the movie in AVI, then you can also change the dimension from the Make Movie Wizard.