Epson MOVERIO BT-100 Guide De L'utilisateur page 21

Press and
slide
As shown in the illustration above, use the switches to widen
the arms to fit your head.
(The switches allow you to adjust the width in three stages with
If you cannot view the top or bottom of the screen,
the widest setting at the top and the narrowest at the bottom.)
remove the lens shade and replace the nose pad.
EN 10