Documentation / User FAQ / Calc / Previous-Next
To create a Note for a cell, use Insert > Note. The Note can be set to show permanently: do a right-click in the cell, then select Show Note. The note can also be set to display when hovering over the cell, if the Tips selection is enabled: Click on Help > Tips. As long as the tick is displayed next to Tips, notes for cells will always be displayed when the mouse hovers over cells with notes.
Documentation / User FAQ / Calc / Previous-Next