Open the preferences by using "Window | Preferences". There is a separate tab for "Cybersecurity". The preferences page provides options to tweak the behavior of all cybersecurity related editors, for example to be less restruct when it comes to define a new threat/asset pair in the Threat Identification table to be able to assign elements not marked as "Assets". This kind of configuration is helpful, if a custom or tailored cybersecurity method is applied, which for example consideres "Attack Surfaces" independent from "Assets".

Note that these settings are user and workspace specific. They are not part of the project state and have no influence on other users, in case the project is shared.