If you want to edit a report, try the following:
1. Tap the up button (i.e. back arrow) in the top left corner
2. On Android, long press (i.e. tap and hold) on the report that you wish to edit. On iOS, select the pencil/edit icon in the top right corner.
3. Select the "Edit Report" option
You can change the name, dates, and default currency of a report from there.