No, i mean something else.
Every individual file should have two buttons. Preview (for loading the image in a lightbox overlay) and a download-button.
When I uncheck the setting ‘Try to Open in Browser instead of download when someone clicks on download link’, the download-button works fine, but I can’t get the image in a lightbox overlay, because it appears that the ‘download-setting’ overrides it.
I’ve attached a screenshot to clarify it.