Settings are stored in a cookie and will take no effect when cookies are disabled in your browser. Only the actual parameters are stored, and unless you check the ‘store cookie’ option at the bottom of the form, the cookie will be deleted at the end of the session. (Note that that the selected configuration only applies to the database application, not to static documents in other sections of the website, which are by default encoded in Unicode.)
In order to view the Collitz-character (see Streitberg 1920, p. 41), you need a Unicode font that supports the Latin Extended-B range. For precomposed polytonic Greek you need a font that supports both the Greek and Greek Extended range. Most modern browsers automatically select an alternative font for code points that are not included in the default font. See Alan Wood’s Unicode Resources for more information on Unicode support in browsers.