I have a Nikon P900 I want pictures with shutter at 1/4000 but its dark how do I change the ISO?

I want to change the ISO manually so where do I change it on my Nikon Coolpix P900 and take super fast photos at the same time? or:I want to change th

I want to change the ISO manually so where do I change it on my Nikon Coolpix P900 and take super fast photos at the same time?

or:I want to change the ISO manually so where do I change it on my Nikon Coolpix P900 and take super fast photos at the same time?

Tags:dark,super,coolpix,