You got 3 members from The Netherlands because at this point is the most active country in this project. When an exchange is registered, the sender gets in line o receive one as well. So, they get selected in that order. This is how "random" works here.
Picking countries or continents would transform this project a lot from what it is now. You cant have "random" and "picking" in the same time.
There are many ways to do exchanges. But I would like this project to remain "random". I like the surprise of it. You don't know who or where.
The only option related to this is to exclude your own country. And I'm not sure that this was very useful either. But its a choice you can make now.