Once you have adjusted your settings and zoomed in you want to adjust the brightness, contrast and tone.
The wording may be different on your software and the icons will vary as to what you click on to open them.
There will probably be many more settings and adjustments on your software but these are the 2 windows I use most of the time and are cirlced in red.
The zoomed in image on the right is the default setting used by the scanner and is too dark.