Taking short clips of iMovie project without modifying the original project?

I am uploading videos (MP4 format) from iMovie directly to YouTube. These videos are roughly 45-50 minutes in length and have had some very basic editing done to them in iMovie such as an intro title screen, transition, text inserted at various places along the project and an exit title screen with text.

So I am successfully uploading the edited project onto YouTube. Now, I want to go into that project and grab three or four shorter clips of, say, 3 to 4 minutes long each and upload those. I know how to grab the clip...that’s not the problem. The problem is that I want to do so WITHOUT modifying any of the editing in the original clip.

Currently, it seems that I can go grab ONE shorter clip from the longer project without modifying the original editing. However, when I go back into the project (now the shorter one because I have shrunk the timeline of the original, longer project) and try to “restretch” the first clip back to it’s original length, all of the editing I did to the original, longer project, is gone and I have to start over.

Is there a way I can “save” the original, longer project so that, as I go and grab these shorter clips from it, I can easily grab them without modifying any of the original editing?

Thank you!