When I upload my video to YouTube it loses most of its tags

I actively create videos for YouTube, however, the tags I type in at the iMovie YouTube prompt screen aren't included on the video once it's uploaded. Let's say for example the first movie I ever upload to YouTube via iMovie I include the tags "hello", "why", and "phone". The second movie I upload I include those three tags and two more: "try" and "dance". The two new tags that weren't included in the movie before, which were "try" and "dance", won't be included in the video once it's uploaded but the tags from the previous video, "hello", "why", and "phone", will. Any ideas on how to fix this? Please and thank you!

P.S. I am on OS X Lion, but it was doing this problem before the upgrade. Also, iMovie is on the most recent version.