Hello Bogdan,
t-code KEA0 in attributes check operating concern currency
refer help links
http://wiki.scn.sap.com/wiki/display/ERPFI/Foreign+Currency+%28FRWAE%29+in+COPA+documents
http://help.sap.com/saphelp_erp60_sp/helpdata/en/7a/4c38c24a0111d1894c0000e829fbbd/content.htm
http://help.sap.com/saphelp_erp60_sp/helpdata/en/7a/4c3a794a0111d1894c0000e829fbbd/content.htm
http://help.sap.com/saphelp_erp60_sp/helpdata/en/7a/4c3d494a0111d1894c0000e829fbbd/content.htm
http://help.sap.com/saphelp_470/helpdata/en/08/51412443b511d182b30000e829fbfe/content.htm
Best regards
Hrusikesh