I have checked into this and I found that there are three data pages that have the $ in them that will need to be updated for the charts to display the other currency symbol.
To update the charts you will need to open these three pages:
DynamicWebCharts > Data > home_data1.php, orders_Chart_Daily_data2.php and orders_Chart_data2.php.
With these three pages open bring up the find with Ctrl+F and set it like this:
Find In: open documents
Search: source code
replace with: %E2%82%AC#val#
Then click on the replace all, it should update the charts to use the Euro symbol instead of the dollar. Let me know if you have any other troubles with this.