You have hidden the navigation panel configuration button. To make it visible again, click the right mouse button on any of the navigation panel buttons and select "Show Configuration Button".
Fe guddioch botwm ffurfweddu y panel llywio. I' w ddangos eto, cliciwch botwm dde y llygoden ar unrhyw fotwm ar y panel llywio a dewiswch "Dangos Botwm Ffurfweddu".