This post is a follow-up to a question from 2017 about setting system options: j.pilet
After a few tries and a call for support, it appears that the specific setting of the "search paths" is not accessible to anyone (despite the Add and Remove buttons in the interface).
If you have a folder indexing problem for the .part search when opening a set, you must add search folders as close as possible to the missing components in "Referenced documents".
If it's a problem of choosing Basemap, there is a dedicated option, in File Locations, which is named: Basemap
Kind regards.