Next is here. Next has been here... This isn't right... Next hasn't even been born yet! How..."
"It's all in the soup."
Most people probably don't realise this, but this forum has had two editors for a number of years. One is the xenForo default editor, and the other is a custom editor I made years back I called BBCEd.
All the settings for which editor you use was lost during the upgrade. You can find the setting under Account Settings > Preferences > Editor.