Wrong UTF-8 "Umlaute" in export

I whant to export my users via the Subscriber-Export function.
In the CSV-File I found “Österreich” instead of "Österreich"
All Umlaute are wrong coded.

I also used the CONVERTTOUTF8 Function and it say:
“The DB was already converted to UTF-8”

I solved the problem! In line 169 from admin/actions/export.php I added the utf8_decode function:

fwrite($exportfile, utf8_decode(quoteEnclosed($value, $col_delim, $row_delim)).$col_delim);

instead of

fwrite($exportfile, quoteEnclosed($value, $col_delim, $row_delim).$col_delim);

I also replaced $col_delim = ‘,’; with $col_delim = ‘;’; in line 82, so Excel knows that this is a CSV File.