The in-game message buffer settings don't work properly
Accessed from the main menu: Settings (E) > Game settings (G) > Message buffer (B)
The "Endless scrolling buffer at the bottom" setting corresponds to having both the stats and two-line buffer both show up at the top.
The "Two-line message buffer at top, stats at bottom" setting corresponds to having the endless scrolling buffer at the bottom.
The "Messages and PC stats at the top (Classic)" setting corresponds to having messages at the top and stats on the bottom. In addition, "messages and PC stats at the top" is not the classic UI.
Whatever setting you choose, ADOM will go back to the endless scrolling buffer whenever you restart it.