The PMail New Mail pop-up used to give the number of new mails downloaded. Now it gives the total number of messages in the New Mail Folder How do I get it back to number of new mails downloaded?

Think you mean the System Message Window.
Windows/System Messages at top.

Under Options / Reporting and loging at bottom is option to check.
Check Show system messages after applying rules.

It will shows info on messages and were moved by rules.
Might be the window got moved off viewable entry, so might want to do windows tile. Also, if you have windows maximize it may end up being behind window.

Christopher, are you talking about the telltale window?

If so, I don't know of a way to change it from showing just the number that were retrieved, let alone change it back.
Suggest a restart if you haven't since it started happening.

Found it. Clicking on the quantity in the telltale window will toggle it between new and total. So, in my image example, clicking the "2 new" will toggle that window to "16 total".

Thanks for your responses. Especially Brian's last one. That works - just done it!