iMovie

Plug into your Mac Book Pro a thumb drive that is formatted Mac OS Extended (Journaled). Create a new library on the thumb drive. Copy, not move, your projects from the old library to the new library. Plug the thumb drive into your iMac. Transfer the new library to your iMac.

However, if your MBP has a newer version of iMovie on it than does your iMac, the projects won’t open on your iMac’s iMovie version. You would need to update the iMac’s iMovie vesion to the identical version that is on your MBP. If your MBP is running an older iMovie version than is on your iMac, then your iMac will update the older library to play the projects. However, the projects will no longer play from that library on your MBP.

That’s why you should leave your old library intact on your MBP, until you are sure that everything is working correctly on your iMac.

In other words, a newer version of iMovie will update the old library so it is not backwards compatible with the old version.

— Rich

Hopefully the info will help you resolve your issue.

One more thing, before moving your projects to the library on the thumb drive, click on the project's icon in the projects browser and do a File/Consolidate Project Media, just to make sure that all media used in the project gets carried over to the new library.

Best,

-- Rich

Make sure that whatever external type of drive you use has sufficient free space to store the library.

Be aware that if you need to reformat a drive the reformatting process will erase all data on the drive. So if the drive contains data from previous use, be sure to back up any data that you want to keep.

-- Rich

A thumb drive is convenient, but you can use any external drive that is formatted Mac OS Extended (Journaled).

-- Rich