I agree! Sometimes I add supplementary information or multimedia files to an item (the parent), and depending on the order added, a different file may be opened by default. I would love to be able to change the primary (child) file associated with an item (parent). Right now, my workaround is to delete the primary file until the desired file is primary, then reattach the deleted file(s). Unfortunately this copies the files so I have to go into the zotero trash and delete the originals at the end of it all. (Using `restore to library` remembers the original settings.)

In more detail, to do the above:
1. right-click the item to `show file` in its directory, leave it open in the background.
2. back in zotero, find the file `move file to trash` if it is not the preferred file.
3. repeat steps 1. and 2. until the shown file is the one you want as the primary file.
4. now drag the file(s) that are open in their directories onto the main (parent) item.
5. find the main (parent) item in the zotero trash (it should be gray) and delete all the files that you moved to trash (there should be a gray and black version of each).

We need a nicer way of doing this.

Bump :)

It seems like this could be an easy fix

Would be nice to get some developer feedback. Is there some unseen complication that makes this feature request difficult to implement?