The document title is displayed as the window title of the PDF document once the PDF has been exported. Assistive Technologies can read out the document title when the PDF document is opened. If your presentation has a title slide, the document title should correspond to the title on the title slide.
It is best to define the document title in the document properties before the conversion:
To do this, click on File in the ribbon and then on the menu item Info on the left-hand side. On the right-hand side of the window, you will now find the category Properties.
You can then edit the document title in the text field Title.
You can also adjust the document title for the PDF document later when exporting PDFs with axesSlide.