That’s odd, looks like the wpsi-settings are not registering correctly. This is the settings group used by the General Settings. The other filter/data blocks have their own group. The wpsi-settings are normally saved in the wp_options table. The easiest way to access this table is through a database manager via your hosting provider, for example PHPMyAdmin.
To exclude admin searches, you can set option wpsi_exclude_admin in the wp_options table to 1
To exclude searches shorter than X characters you can set the wpsi_min_term_length option to the amount of characters you want to set as the limit, for example 3 or 5
It’s hard to say what’s causing this without being able to reproduce it. Could you check if the wpsi_exclude_admin and wpsi_min_term_length entries even exists in the wp_options table?