I'm able to reproduce the bug using
v3.1 on a Windows7 PC. To be precise, I took screenshots of what the OP is saying:
I have the preference: Fiat=>Show History Rates checkbox set.
![failed_loading_img](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2F9XTNQiz.jpg&t=665&c=V48szI1oakAjvw)
When I then select the menu item "Edit Description" using the context menu in the history tab, it gives me editing the EUR value instead of the actual description.
Return to the Main Screen and Right-Click any previous transaction to open the context menu, then select "
Edit Description".
That should make the Default Description of the address or the transaction
editable but instead, the USD value is the one that became editable:
![failed_loading_img](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2FtiCgl8A.jpg&t=665&c=S9wlXAPsUZX2hA)
t.n: I've written texts on the images.
---Edit---The bug is now resolved.