Hi
"......Once the video has been exported, I can't skip to different parts of the video, I have no choice but to watch it all each time....."
If you export the project as a Video file to your PC (even if you have added bookmarks then that is correct.
If, on the other hand you export your project as DVD Movie Disc then the bookmarks can set to be interpreted as chapters by the disc player. This will happen if you use the burner associated with VP in which you set the bookmarks as you create the project or the NCH standalone burner Express Burn in which you can set chapters at selected points before you burn the disc.
The usual AR for landscape format is 16:9 (1:1.777) e.g. 1280 x 720 or 1920 x 1080. All clips with this AR will fill the frame. The same will happen if a clip is Zoomed to a 16:9 AR. or scaled above 1. These options are usually used when the original clip is NOT 16:9 or an an area within the frame needs to be enlarged.
Scaled to a value below 1 (even if the AR is kept 16:9 ) will result in a smaller image that is not full frame.Cropping will have the same effect unless you 16:9 zoom as well. Exporting at a different format (AR) to your constituent clips can also result in black borders or unexpected size changes. Always try to export with the same parameters as your clips.
Nat