You can specify the HTML page title for a particular output file more than one way. For example, in general you might want to use the paragraph-format method (which applies to all files), then override that method with a Title marker or a [Titles] assignment for selected files. Table 27-1 shows which method takes precedence if more than one method applies to a given output file.
If you do not specify any page titles, the default title for each output file is Test File from DITA2Go; any other title specification overrides this default. If some of your output files show Test File from DITA2Go as the title, this means you did not manage to specify titles for those files. See §27.5.2.6 Assigning a default title.