If you are moving from iMovie 9, version 10.2.5 will create a new library and copy your projects over, rather than replacing the old files.

Downloading system software from third-party sites carries risks. Always prioritize official or verified methods.

This is the safest method to ensure you have a signed, malware-free version of the app. on your Mac. Search for If you have a compatible macOS, click 2. Manual Update via Apple Support

Assuming you have obtained a legitimate file, here is the safe installation process:

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