Who establishes the value of the foreign currency? There are two actors that influence on the final quotation of the foreign currencies. The first one is the market law regulated by the supply and demand; and in second place the goverment politics that through the Central Bank set up the value of the foreign currency fixing it in front of the dollar, according to the economic model.
There are countries in Latinamerica where the value of the local foreign currency is devaluated in front of the dollar to help exports and generate the income of dollars through the sale of their products abroad.
These advantages that have the regional economies in Latinamerica are helped with the devaluation of the local currency and the increase of the value of the reference foreign currency, in this case the dollar.
Even if actually the value of the foreign currency is compared to the value of the dollar as reference currency, today the American currency has not the force that it used to have 50 years ago, and it can be said that slowly the dollar is getting into a one way tunnel.
The value of the foreign currency is based on the maintenance of the macroeconomic variables in orden an with superavit, so that income is greater than expenditure. Actually the United States have made the deficit a way of maintain many economies, especially the Asian ones. In incredible to think that Asian countries as Indonesia exports capital to United States instead of being the opposite, but this happens.
The United States have done that countries with commercial surplus invest their own saving in United States, becoming moneylenders of this country buying Exchequer bonds. The authorities of the Federal Reserve are sure that their commercial partners will always be forced to buy more American debt to avoid the definitive collapse of the foreign currency value and of the monetary global system.