Carol, there's a major problem following the upgrade. I use the Firefox web browser under Windows 10, and if I click the "Quote" button, I get the "Post your reply" screen, but the area of the page where the message editor should appear is completely blank. Doing the same thing with the "Edge" browser (which I dislike!) works fine.
The Quick Editor (which I'm using to write this) works fine on both browsers.
Can you investigate this anomaly, please?