B&W assignment

You're not a problem at all. Yes, you can use the button. It's like using auto, though. It changes it to the way IT thinks it should look. What program are you using? Even the most basic programs usually have a Hue/Saturation button.

Edited to add: That might be just your programs way of using the desaturation mode.

I use Jasc Paint Shop Photo and sometimes Microsoft Digital Image 2006 Starter Edition Editor.

I just deleted that program from my computer. It was the very first one that I used. I wasn't very good at it. I got PhotoShop Elements because it was recommended as been very easy. I needed the space on my computer. I'm sure it has Hue/Saturation. See if there isn't something like Adjustments and look under that.