cannot change plugin settings from dashboard

Hi!

This sounds like that either the scripts are not loaded at all, or some other script might be causing an execution error before the search back-end scripts are loaded.

The only way to test this, is to try disabling all plugins one-by-one, whilst reloading the search back-end. At some point it should start working.
A theme script could also cause this, so switching to the default theme temporarily could help determining the source of the issue.

If none of these work, then it could mean a corrupted file or perhaps a browser extension that might block one of the scripts. Completely re-installing the plugin and trying it in incognito mode could help.

Le me know!