Quick Time Pro: How can I change Metadates in a video? When I Process a video and save it it gets the actual date. I want the original one.

I have a sequence of photos and videos taken with the same camera ( Canon ) . When I process a video and save it it looses the original date and gets the actual one. Thus it fells out of that photo/video sequence. I want it back at the place where it was. How can I change the respective Metadate?

Thanks for any advice.

Klaus Mueller