Ex post, savings have to equal investment in a closed economy, i.e. the world. So, if one points to a particular country, say China, where savings have exceeded investment and there is a current account surplus, then by definition there is another country (or countries such as the UK or USA) where savings have been below investment and there is a current account deficit. What we need to look at is the ex ante desired savings versus investment dynamics on a global scale, and think of the equilibrating interest rate as a global price.
