Do you know how I can also remove the bIg icons in my left hand pane which I have also recently started to see? Many thanks .
It depends on what pane you are referring to.
If it is the folder pane or sidebar, there will be small account avatars next to each account’s main folder. You can’t remove those.
If it is the message list, then these avatars can be removed by right-click in the message header row, and unticking the Avatar option. If you are using the single line layout, right-click in the header row and choose Columns Configuration, then remove the Avatar option from the right column.