Grease or oil the hinges to make opening and closing the doors easier. Ensure that the container is on flat, level ground. If not on level ground, the frame may twist making it difficult to open and close the doors. This is a regular problem with shipping containers; the industry term is 'racked'. The cause of the door/s not closing is because the container isn't sitting flat, which is different to being 'level'. The container can be placed on a slope & it will open & close easily as long as the surface it is sitting on is flat.