whats a good setting to change to help a camera take a better photo w/o overkilliing the dark corners?

I wasn’t able to take dark pictures with my camera until i upped a iso setting and now these are what it takes
(finepix 6.3 maga pixel)

some example picts, i cut corner out of yoshi pic

also would moving my ikea reflector back away from the bulb help with dark corners? In real lif there only a hair darker, which is great considering my larger 19 inch lcd