It used to be that if you looked at achievements, the last achievement you were looking at was what it would open to when you closed it (when staying on the same character and not logging out).
Now it resets every time you open the achievement menu. Worse is if you're in a group and looking at achievements and someone in your group starts a fight, it will reset the achievement menu while you're looking at it still.
I think whatever was done to redo the achievement menu screwed that up. It needs to go back to how it was before, so it doesn't change what you're looking at or reset what you were looking at just because you closed the menu. It takes too much extra clicking to get back to where you were.