On my screen shot...
I was trying to fill individual hexes (which I had made by cloning) with a paint color. I was not happy with the way the paint didn't fill all the white in the hex unless I was at a high magnification (too high for me to do what I wanted, as the hexes I wanted to paint are 19 hexes away from each other). I was reading about "closing gaps" and trying to learn.
I saw the paint color selector in the bottom left hand corner of the screen. I clicked around in there. I saw "O" could move up to 2, but then I moved it back down to zero, because I didn't know what it did. I also noticed that there was a seemingly identical paint color selector in the top right hand part of the screen. At this point, I was trying to remove some paint I had put in a hex, and I was selecting the X for "no paint" but that wasn't taking out the paint I had put in there. I hit control-x, but I had to hit it a BUNCH of times. Then I noticed that no matter what color I selected, the paint tool wasn't working. But it was registering the action, because I could control-x and it would undo the unseen action I had done when I clicked on a hex. I noticed the paint colors in the two boxes (top right and bottom left) were now different colors. I couldn't fix it.
I saved my work. closed the program. Reopened it. Still the same problem. I don't know what I did or where to hit "reset" to take it back to the default conditions.
Thank you for your time and patience.
BHD