Set search results to all search words as default in responsive help

Hi,

I am using responsive HTML5 help in Robohelp 2015. There is an option for users to tick a box for all search words for an AND search otherwise the default is OR.

Can this be set as default - so that the box is automatically ticked for an AND search?

There isn't an option for this so I guess it will require a code change but I haven't manage to locate the code yet.

Thanks