Hello. I have selected the US Dollar currency for the Global Admin user. Is it possible to choose different currency for the Reseller of same Global Admin?

Yes, Reseller can have "Selling and Reporting Currency" different than the GlobalAdmin. Lets say if Global Admin is charging reseller in USDs, then it is not mandatory that Reseller must have to select USD as their selling currency too. Rather Reseller can have his own selling currency EURO or any other non-USD currency.