Why was US participation in the international economic system vital?

for exchange-rate stabilization.

Could someone explain this to me. I've already gone through websites.

this was during FDR's presidency

We needed to trade goods with the world. This was most efficient when we knew from one month to the next what the dollar was worth compared with other currencies.

but when the US withdrew from exchange-rate stabilization, how was this a bad thing for other countries?

The exchange rate also determined the profit made from goods bought from and sold to other countries.

for the second question:

was it because the US was buying from other countries?

like mainly the US

What is your second question?

Please clarify your answer.