I have a Canon A70 that uses four AAs. I always put the spare, freshly changed batteries in the carrier with their polarities alternating, one after another; in other words, battery no. 1 has + facing up, battery no. 2 has - facing up, etc. When I change batteries, I drop the spent batteries out of the camera and slip the new ones in--if you practice you wont have to fuss with getting the new batteries oriented right, you can just drop them right in. Then I take the old ones and put them in the carrier with there polarities matching, thus avoiding the embarrassment of putting spent batteries back into the camera.