Editing metadata of books (title, author) doesn't change metadata on device?

[supafastjelifish]

Hi everyone, I'm new to using Calibre as I've just bought a new ereader for the first time in over a decade! I've switched tothe Pocketbook Verso Pro BW from the Sony PRS T2.

Many of my books' metadata is formatted strangely, but what is most important to me for indexing is author name and title (and release date, though I haven't played around with editing this). I can't edit the metadata of the books on the device while it's plugged in so I've been matching them to the same books in my library that I've fixed (aside from me editing author and title, they're the same files). When I unplug the device, the titles and author names haven't changed.

What am I missing? Thanks