After making a selection in the diagram, all the values selected can be moved by using Ctrl+Up and Ctrl+Down. It will shift all the selected values up or down one unit, which normally is either one MWh or kWh depending on the series selected.

By using Ctrl+Left/Alt+Left and Ctrl+Right/Alt+Right the selection the selection could be adjust either left or right by one timestep unit, which usually is by one hour. Ctrl+Left/Right will move the right end border of the selection and Alt+Left/Right will move the left border.