add the slot updateDisplayUnit() to overviewpage, sendcoinsdialog, sendcoinsentry and connect it to displayUnitChanged() - this ensures all fields in the GUI, who use a display unit are imediately updated, when the user changes this setting in the optionsdialog / ensure used fields init with the current set display unit

src/qt/sendcoinsentry.h

@@ -45,6 +45,7 @@ private slots:
     void on_payTo_textChanged(const QString &address);
     void on_addressBookButton_clicked();
     void on_pasteButton_clicked();
+    void updateDisplayUnit();
 
 private:
     Ui::SendCoinsEntry *ui;