PD versions share downloaded and extra content, but you will likely lose the transitions again if you uninstall PD16.
I actually don't have any "momentum" transitions installed in my version of PD17, and I've been upgrading since PD9. Do you know if they came with an add-on pack?
If they did, you would see it listed separately on Windows' Apps & features (uninstall) screen, like this:
If a separate add-on/plug-in is listed there, you should be able to uninstall just the main PD16 app from the same screen. Be sure to keep your personal settings if you're prompted to delete them.
YouTube/optodata
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