- highlight a folder and set it with all your preferred options - now, click the icon to the right of the 'quick filters' button above message view list - near the bottom of the opened menu is 'apply current view to' click that - and then click the subfolders option and then click the account name to apply the selected view to all folders in the account. - repeat above for all accounts.

Oops. that shows number of unread. That's not what you wanted. To see unread, - place mouse on unified tool bar and rightclick and select customize - locate the View icon and drag to unified tool bar and save - now click the View icon and select 'unread'

Thanks. I think a combination of the two has got me much improved!

In your first reply, to be sure I have picked the right one, my icon was actually on the right of the line that contains subject, date etc? (Image attached)

In your second reply, I couldn't drag the View icon to the menu, but presumably that's because I already had a View menu next to File and Edit?

But that was very helpful and I've found things I didn't know about before :-)

Thanks

In your second reply, I couldn't drag the View icon to the menu, but presumably that's because I already had a View menu next to File and Edit?

No he is talking about customizing the toolbar. See https://support.mozilla.org/en-US/kb/unified-toolbar

Not the menu bar.

This is what the View when entered on my rather cluttered toolbar looks like.

I use it rather a lot to switch between all and unread messages in some folders as I have the mail generally threaded, but by only showing the unread mail I don't see the mass of read mail unless the email leads me to see more on the topic.