In very simplistic terms the root problem post-Great War was the imbalance of gold held by the USA, pre-war the major economies were equivalent in their holdings but post-war the USA held almost as much as the UK, France and Germany, with Russia now off-line too. Thus to make gold work the USA needed to run a trade deficit and outflow gold, importing from Europe and creating a parity that would restore global trade flows. The USA instead horded the gold as if it was of value and things got worse under FDR who upped the purchase price from $20 to $35/ounce, creating another inflow and destroying gold as a medium of international trade. Bretton Woods formalized this and simply masked the gold horde behind the Dollar as its substitute. The free float finally putting us back to a working medium to exchange goods or services in different monies. Thus I suggest attacking the gold reserve, its pricing, the ability to keep Dollars in lieu of gold or any agreement at all, these will alter the "gold standard" and shorten the Dollar as the de facto gold currency. I did this with my altered Great War, the USA unhinging the gold standard and breaking it under a similar gold price change but with a German led Euro-bloc and surviving Sterling zone the USA cannot get to Bretton Woods, gold becomes useless with the USA holding too much sterilized, so the free float comes earlier. Global trade stays sticky behind protection barriers and high tariffs, but the opposing trade zones are closer in size, eventually weakening the barriers and revitalizing trade based on currency exchanges, maybe, a big maybe, getting gold as the common peg, the USA strength edging Dollars in as the neutral currency, something central bankers likely enjoy as it forces certainty over exchanges. Perhaps you can find a different WW2 and post-war that puts Bretton Woods on shakier ground, or rises the other trade partners faster and breaks the Dollar monopoly. I suggest a British hold on oil that shortcuts the American moves to create a Petrodollar. That might get you there.
