Thanks. The foreground color is the one selected. When I click a swatch the background color is replaced. When I click on either the foreground or background square in the Coloro Panel it just opens the Color Picker Window.
It can be hard to tell which color chip in the color panel is actually the active one.
The active color chip in the color panel will have either a white or grey line around it, depending on the ui interface color photoshop is using)
When you use the eyedropper are you using any modifier key like Command.
You shouldn't need to use any modifier key with the Brush Tool selected and clicking on one of the swatches in the Swatches panel to set the foreground color.
(with the brush tool selected, holding down the command key while clicking on one of the swatches will set the background color in the toolbox)
If nothing seems to work, i would reset the photoshop preferences
Press and hold the Shift+Command+Option keys just after starting the launch of photoshop
Keep holding the keys down until you get a dialog asking if you want to delete the adobe photoshop settings file