To install the Zoomer, run Setup executable as usual.
To associate image files supported by the Zoomer later, click a tool bar button
Options
and About, and click a button Associations there. In the Associations dialog,
select desired file types, and click Associate.

If you uncheck some file types registered to the Zoomer and click Associate those associations are restored to a previous state. But if the application earlier associated with such file types were installed, such files can not be opened from the Explorer window by a mouse double click.