How to scroll up and down in sliced "screen" terminal

1.Ctrl+A, then Esc
2. After that, you should be able to move your cursor around using the arrow keys:
↑, ↓, PgUp, PgDn and sometimes using the mouse wheel
3. Return control: Q or Esc

Press Ctrl-a then [ will enter the copy mode, and you can scroll up and down like vim editor. Leave the copy mode by pressing Escape.