Recently I've noticed that whenever I try to add an effect, it affects ALL elements as opposed to just the selected object.

The first time I noticed, I thought it would go away when I restart the computer but it's still happening! In the screenshot below, the top left was indeed the only one that got the dropshadow treatment but as soon as I hit that add dropshadow button, all the box changed their colors (see the purple and blue box)

Tried Googling for a solution but couldn't find any. Anybody experienced(ing) the same thing? How did you fix it?