How to change the library filename in sync preferences?

I installed X20. Instead of opening the old library file that I had been using with X8, I used the option of creating a new library file (with a new name) and then imported references from my old library file into X20. When I go to Edit->Preferences->Sync, the name displayed in the “Sync this Endnote library” is still the old library filename - not the one that I created using X20. It doesn’t allow me to change the library filename. How shall I change this old filename to the new one?

The best process for moving your references to EndNote 20 without actually converting your old file would be to create a new library in EndNote 20, and then instead of importing your records from EndNote X8, trigger the Sync process on that new library.
This is basically the same process for synchronizing your records on a new machine.
You’ll be prompted to Merge the library to combine the two, and your records will populate into your new library from the EndNote Online service (complete with groups).

It should also be noted that converting your EndNote X8 library to EndNote 20 will generate a new “Converted” version of the file, which should allow you to continue synchronizing seamlessly with the converted library, and not affect the actual EndNote X8 library itself.

Otherwise, EndNote updates the Sync Preference for the target library when it’s synchronized. There’s no other way to change the actual indicated library in that preference setting.