Most of the information that BE needs lives in the bug repository itself, but there is user-specific information that does not fit into a shared repository. This per-user configuration information is stored in an INI-style config file:
[default] user = 'John Doe <email@example.com>'
The config file is located at ~/.config/bugs-everywhere by default, but you can override the path by setting environment variables (see path() for details).
Currently the only information stored in the configuration file is a user ID (see get_user_id()), as shown in the example above. However, many version control systems allow you to specify your name and email address, and BE will fall back to the VCS-configured values, so you probably don’t need to set a BE-specific configuration.