It looks as though I may have to change a reservation that I made with Rail Europe - basically changing from a journey Milano Garibaldi to Roma Termini to a different time leaving from Milano Centrale to Roma Termini.
I saw that there was an earlier posting on this site that offered the guidance:
https://help.raileurope.co.uk/article/41286-exchanging-tickets#account
However this guidance implies that there is a button: exchange options and I cannot see that on my Rail Europe app.
