Hey all,
this is a know bug which was fixed with version 27.
The colleagues from development have created a query that selects € and sets it for all users.
Please create a backup before using a SQL on your idoit database.
Dollar = C__CMDB__CURRENCY__DOLLAR
Pound = C__CMDB__CURRENCY__POUND
Schweizer Franken = C__CMDB__CURRENCY__SWISS_FRANC
Select your data database and use
UPDATE isys_user_locale SET isys_user_locale__isys_currency__id = (SELECT isys_currency__id FROM isys_currency WHERE isys_currency__const = 'C__CMDB__CURRENCY__EURO');