GS wrote:

In Excel 365 I inserted some new rows and this format symbol
appeared.

https://dl.dropboxusercontent.com/u/...-Pasting-1.jpg

What exactly should I have done with it? What I actually did was to
click 'Format same as above'. Nothing obvious happened. In
particular, the symbol did not go away. How do I remove it, as it's
rather distracting?

Press the ESC key makes it disappear.

Thanks Garry. Yep, discovered that embarrassingly obvious solution
shortly after posting. (Pity there's no reliable way to delete posts!)

Usually, clicking elsewhere also does it, but not in this case.

--
Terry, East Grinstead, UK