Would a single worldwide currency solve lots of problems? (Details )

I hear so much about how the value of each nation’s currency and exchange rates rise and fall in a reactive way to current events. The world’s economy can all fall to crap if some of the bigger,more powerful countries make economic mistakes. The EU used to provide financial security to the member nations. The greedy assholes running Wallstreet made a huge mistake, and the world has been in a bind since. (2008)

I hear of a nation’s currency being used as a weapon. After Putin annexed the Crimean Peninsula the world tried to devalue Russian money. This type of behavior could lead to world war. (I’m not saying sanctions aren’t a good option in certain cases. )
It seems a single currency, globally accepted, could add stability to the world. Each country could receive an amount of ‘credit’ of this money to use as they would normally use their own currency,or something.

With the Internet, it seems feasible. Kind of like my limited understanding of Bit coin.

So….

Is it even possible? Would it alleviate some of the problems in our world?