Problem with music library after update from version 5 to 7

I recently got a different controller and switched from Rekordbox 5 to Rekordbox 7 (I also briefly installed Rekordbox 6 because I didn’t know 7 had been released). Now I'm facing the following issue. I have my music library on an external HDD. When I change the drive in the settings to "untitled" (which is my external HDD), it picks up an old music library. It seems that the correct library is on my laptop’s hard drive (without the music files), while my music files and old library are on the external HDD. How can I get everything back onto my external HDD? I also have a new empty HDD available if that would help to set everything up properly.